Earlene  Rowe

Earlene Rowe

1596343200

Top Vue Packages for Adding Charts, Unique IDs, Sliders & Scroll Lock

Vue.js is an easy to use web app framework that we can use to develop interactive front end apps.

In this article, we’ll look at the best packages for adding charts, unique IDs, sliders, and scroll lock.

vue-unique-id

vue-unique-id lets us add a unique ID to our Vue component.

To use it, we run:

npm i vue-unique-id

to install it.

Then we write:

main.js

import Vue from "vue";
import App from "./App.vue";
import UniqueId from "vue-unique-id";
Vue.use(UniqueId);
Vue.config.productionTip = false;
new Vue({
  render: h => h(App)
}).$mount("#app");

App.vue

<template>
  <div id="app"></div>
</template>

<script>
export default {
  created() {
    console.log(this.uid);
  }
};
</script>

We register the plugin and use the this.uid property to get the unique ID.

Also, we can get the ID with the $id method.

For instance, we can write:

<template>
  <div id="app"></div>
</template>

<script>
export default {
  created() {
    console.log(this.$id("foo"));
  }
};
</script>

to get an ID with the 'foo' suffix added to it.

VueVisible

VueVisible is a directive that lets us display something conditionally.

To use it, we run:

npm i vue-visible

to install it.

Then we use it by writing:

<template>
  <div id="app">
    <div v-visible="isVisible">I'm visible</div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isVisible: true
    };
  }
};
</script>

We just use the v-visible directive like the v-show directive to conditionally display something.

#javascript #software-development #programming #web-development #vue #vue.js

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Top Vue Packages for Adding Charts, Unique IDs, Sliders & Scroll Lock

Rufus Scheduler: Job Scheduler for Ruby (at, Cron, in and Every Jobs)

rufus-scheduler

Job scheduler for Ruby (at, cron, in and every jobs).

It uses threads.

Note: maybe are you looking for the README of rufus-scheduler 2.x? (especially if you're using Dashing which is stuck on rufus-scheduler 2.0.24)

Quickstart:

# quickstart.rb

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.in '3s' do
  puts 'Hello... Rufus'
end

scheduler.join
  #
  # let the current thread join the scheduler thread
  #
  # (please note that this join should be removed when scheduling
  # in a web application (Rails and friends) initializer)

(run with ruby quickstart.rb)

Various forms of scheduling are supported:

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

# ...

scheduler.in '10d' do
  # do something in 10 days
end

scheduler.at '2030/12/12 23:30:00' do
  # do something at a given point in time
end

scheduler.every '3h' do
  # do something every 3 hours
end
scheduler.every '3h10m' do
  # do something every 3 hours and 10 minutes
end

scheduler.cron '5 0 * * *' do
  # do something every day, five minutes after midnight
  # (see "man 5 crontab" in your terminal)
end

# ...

Rufus-scheduler uses fugit for parsing time strings, et-orbi for pairing time and tzinfo timezones.

non-features

Rufus-scheduler (out of the box) is an in-process, in-memory scheduler. It uses threads.

It does not persist your schedules. When the process is gone and the scheduler instance with it, the schedules are gone.

A rufus-scheduler instance will go on scheduling while it is present among the objects in a Ruby process. To make it stop scheduling you have to call its #shutdown method.

related and similar gems

  • Whenever - let cron call back your Ruby code, trusted and reliable cron drives your schedule
  • ruby-clock - a clock process / job scheduler for Ruby
  • Clockwork - rufus-scheduler inspired gem
  • Crono - an in-Rails cron scheduler
  • PerfectSched - highly available distributed cron built on Sequel and more

(please note: rufus-scheduler is not a cron replacement)

note about the 3.0 line

It's a complete rewrite of rufus-scheduler.

There is no EventMachine-based scheduler anymore.

I don't know what this Ruby thing is, where are my Rails?

I'll drive you right to the tracks.

notable changes:

  • As said, no more EventMachine-based scheduler
  • scheduler.every('100') { will schedule every 100 seconds (previously, it would have been 0.1s). This aligns rufus-scheduler with Ruby's sleep(100)
  • The scheduler isn't catching the whole of Exception anymore, only StandardError
  • The error_handler is #on_error (instead of #on_exception), by default it now prints the details of the error to $stderr (used to be $stdout)
  • Rufus::Scheduler::TimeOutError renamed to Rufus::Scheduler::TimeoutError
  • Introduction of "interval" jobs. Whereas "every" jobs are like "every 10 minutes, do this", interval jobs are like "do that, then wait for 10 minutes, then do that again, and so on"
  • Introduction of a lockfile: true/filename mechanism to prevent multiple schedulers from executing
  • "discard_past" is on by default. If the scheduler (its host) sleeps for 1 hour and a every '10m' job is on, it will trigger once at wakeup, not 6 times (discard_past was false by default in rufus-scheduler 2.x). No intention to re-introduce discard_past: false in 3.0 for now.
  • Introduction of Scheduler #on_pre_trigger and #on_post_trigger callback points

getting help

So you need help. People can help you, but first help them help you, and don't waste their time. Provide a complete description of the issue. If it works on A but not on B and others have to ask you: "so what is different between A and B" you are wasting everyone's time.

"hello", "please" and "thanks" are not swear words.

Go read how to report bugs effectively, twice.

Update: help_help.md might help help you.

on Gitter

You can find help via chat over at https://gitter.im/floraison/fugit. It's fugit, et-orbi, and rufus-scheduler combined chat room.

Please be courteous.

issues

Yes, issues can be reported in rufus-scheduler issues, I'd actually prefer bugs in there. If there is nothing wrong with rufus-scheduler, a Stack Overflow question is better.

faq

scheduling

Rufus-scheduler supports five kinds of jobs. in, at, every, interval and cron jobs.

Most of the rufus-scheduler examples show block scheduling, but it's also OK to schedule handler instances or handler classes.

in, at, every, interval, cron

In and at jobs trigger once.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.in '10d' do
  puts "10 days reminder for review X!"
end

scheduler.at '2014/12/24 2000' do
  puts "merry xmas!"
end

In jobs are scheduled with a time interval, they trigger after that time elapsed. At jobs are scheduled with a point in time, they trigger when that point in time is reached (better to choose a point in the future).

Every, interval and cron jobs trigger repeatedly.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.every '3h' do
  puts "change the oil filter!"
end

scheduler.interval '2h' do
  puts "thinking..."
  puts sleep(rand * 1000)
  puts "thought."
end

scheduler.cron '00 09 * * *' do
  puts "it's 9am! good morning!"
end

Every jobs try hard to trigger following the frequency they were scheduled with.

Interval jobs trigger, execute and then trigger again after the interval elapsed. (every jobs time between trigger times, interval jobs time between trigger termination and the next trigger start).

Cron jobs are based on the venerable cron utility (man 5 crontab). They trigger following a pattern given in (almost) the same language cron uses.

 

#schedule_x vs #x

schedule_in, schedule_at, schedule_cron, etc will return the new Job instance.

in, at, cron will return the new Job instance's id (a String).

job_id =
  scheduler.in '10d' do
    # ...
  end
job = scheduler.job(job_id)

# versus

job =
  scheduler.schedule_in '10d' do
    # ...
  end

# also

job =
  scheduler.in '10d', job: true do
    # ...
  end

#schedule and #repeat

Sometimes it pays to be less verbose.

The #schedule methods schedules an at, in or cron job. It just decides based on its input. It returns the Job instance.

scheduler.schedule '10d' do; end.class
  # => Rufus::Scheduler::InJob

scheduler.schedule '2013/12/12 12:30' do; end.class
  # => Rufus::Scheduler::AtJob

scheduler.schedule '* * * * *' do; end.class
  # => Rufus::Scheduler::CronJob

The #repeat method schedules and returns an EveryJob or a CronJob.

scheduler.repeat '10d' do; end.class
  # => Rufus::Scheduler::EveryJob

scheduler.repeat '* * * * *' do; end.class
  # => Rufus::Scheduler::CronJob

(Yes, no combination here gives back an IntervalJob).

schedule blocks arguments (job, time)

A schedule block may be given 0, 1 or 2 arguments.

The first argument is "job", it's simply the Job instance involved. It might be useful if the job is to be unscheduled for some reason.

scheduler.every '10m' do |job|

  status = determine_pie_status

  if status == 'burnt' || status == 'cooked'
    stop_oven
    takeout_pie
    job.unschedule
  end
end

The second argument is "time", it's the time when the job got cleared for triggering (not Time.now).

Note that time is the time when the job got cleared for triggering. If there are mutexes involved, now = mutex_wait_time + time...

"every" jobs and changing the next_time in-flight

It's OK to change the next_time of an every job in-flight:

scheduler.every '10m' do |job|

  # ...

  status = determine_pie_status

  job.next_time = Time.now + 30 * 60 if status == 'burnt'
    #
    # if burnt, wait 30 minutes for the oven to cool a bit
end

It should work as well with cron jobs, not so with interval jobs whose next_time is computed after their block ends its current run.

scheduling handler instances

It's OK to pass any object, as long as it responds to #call(), when scheduling:

class Handler
  def self.call(job, time)
    p "- Handler called for #{job.id} at #{time}"
  end
end

scheduler.in '10d', Handler

# or

class OtherHandler
  def initialize(name)
    @name = name
  end
  def call(job, time)
    p "* #{time} - Handler #{name.inspect} called for #{job.id}"
  end
end

oh = OtherHandler.new('Doe')

scheduler.every '10m', oh
scheduler.in '3d5m', oh

The call method must accept 2 (job, time), 1 (job) or 0 arguments.

Note that time is the time when the job got cleared for triggering. If there are mutexes involved, now = mutex_wait_time + time...

scheduling handler classes

One can pass a handler class to rufus-scheduler when scheduling. Rufus will instantiate it and that instance will be available via job#handler.

class MyHandler
  attr_reader :count
  def initialize
    @count = 0
  end
  def call(job)
    @count += 1
    puts ". #{self.class} called at #{Time.now} (#{@count})"
  end
end

job = scheduler.schedule_every '35m', MyHandler

job.handler
  # => #<MyHandler:0x000000021034f0>
job.handler.count
  # => 0

If you want to keep that "block feeling":

job_id =
  scheduler.every '10m', Class.new do
    def call(job)
      puts ". hello #{self.inspect} at #{Time.now}"
    end
  end

pause and resume the scheduler

The scheduler can be paused via the #pause and #resume methods. One can determine if the scheduler is currently paused by calling #paused?.

While paused, the scheduler still accepts schedules, but no schedule will get triggered as long as #resume isn't called.

job options

name: string

Sets the name of the job.

scheduler.cron '*/15 8 * * *', name: 'Robert' do |job|
  puts "A, it's #{Time.now} and my name is #{job.name}"
end

job1 =
  scheduler.schedule_cron '*/30 9 * * *', n: 'temporary' do |job|
    puts "B, it's #{Time.now} and my name is #{job.name}"
  end
# ...
job1.name = 'Beowulf'

blocking: true

By default, jobs are triggered in their own, new threads. When blocking: true, the job is triggered in the scheduler thread (a new thread is not created). Yes, while a blocking job is running, the scheduler is not scheduling.

overlap: false

Since, by default, jobs are triggered in their own new threads, job instances might overlap. For example, a job that takes 10 minutes and is scheduled every 7 minutes will have overlaps.

To prevent overlap, one can set overlap: false. Such a job will not trigger if one of its instances is already running.

The :overlap option is considered before the :mutex option when the scheduler is reviewing jobs for triggering.

mutex: mutex_instance / mutex_name / array of mutexes

When a job with a mutex triggers, the job's block is executed with the mutex around it, preventing other jobs with the same mutex from entering (it makes the other jobs wait until it exits the mutex).

This is different from overlap: false, which is, first, limited to instances of the same job, and, second, doesn't make the incoming job instance block/wait but give up.

:mutex accepts a mutex instance or a mutex name (String). It also accept an array of mutex names / mutex instances. It allows for complex relations between jobs.

Array of mutexes: original idea and implementation by Rainux Luo

Note: creating lots of different mutexes is OK. Rufus-scheduler will place them in its Scheduler#mutexes hash... And they won't get garbage collected.

The :overlap option is considered before the :mutex option when the scheduler is reviewing jobs for triggering.

timeout: duration or point in time

It's OK to specify a timeout when scheduling some work. After the time specified, it gets interrupted via a Rufus::Scheduler::TimeoutError.

scheduler.in '10d', timeout: '1d' do
  begin
    # ... do something
  rescue Rufus::Scheduler::TimeoutError
    # ... that something got interrupted after 1 day
  end
end

The :timeout option accepts either a duration (like "1d" or "2w3d") or a point in time (like "2013/12/12 12:00").

:first_at, :first_in, :first, :first_time

This option is for repeat jobs (cron / every) only.

It's used to specify the first time after which the repeat job should trigger for the first time.

In the case of an "every" job, this will be the first time (modulo the scheduler frequency) the job triggers. For a "cron" job as well, the :first will point to the first time the job has to trigger, the following trigger times are then determined by the cron string.

scheduler.every '2d', first_at: Time.now + 10 * 3600 do
  # ... every two days, but start in 10 hours
end

scheduler.every '2d', first_in: '10h' do
  # ... every two days, but start in 10 hours
end

scheduler.cron '00 14 * * *', first_in: '3d' do
  # ... every day at 14h00, but start after 3 * 24 hours
end

:first, :first_at and :first_in all accept a point in time or a duration (number or time string). Use the symbol you think makes your schedule more readable.

Note: it's OK to change the first_at (a Time instance) directly:

job.first_at = Time.now + 10
job.first_at = Rufus::Scheduler.parse('2029-12-12')

The first argument (in all its flavours) accepts a :now or :immediately value. That schedules the first occurrence for immediate triggering. Consider:

require 'rufus-scheduler'

s = Rufus::Scheduler.new

n = Time.now; p [ :scheduled_at, n, n.to_f ]

s.every '3s', first: :now do
  n = Time.now; p [ :in, n, n.to_f ]
end

s.join

that'll output something like:

[:scheduled_at, 2014-01-22 22:21:21 +0900, 1390396881.344438]
[:in, 2014-01-22 22:21:21 +0900, 1390396881.6453865]
[:in, 2014-01-22 22:21:24 +0900, 1390396884.648807]
[:in, 2014-01-22 22:21:27 +0900, 1390396887.651686]
[:in, 2014-01-22 22:21:30 +0900, 1390396890.6571937]
...

:last_at, :last_in, :last

This option is for repeat jobs (cron / every) only.

It indicates the point in time after which the job should unschedule itself.

scheduler.cron '5 23 * * *', last_in: '10d' do
  # ... do something every evening at 23:05 for 10 days
end

scheduler.every '10m', last_at: Time.now + 10 * 3600 do
  # ... do something every 10 minutes for 10 hours
end

scheduler.every '10m', last_in: 10 * 3600 do
  # ... do something every 10 minutes for 10 hours
end

:last, :last_at and :last_in all accept a point in time or a duration (number or time string). Use the symbol you think makes your schedule more readable.

Note: it's OK to change the last_at (nil or a Time instance) directly:

job.last_at = nil
  # remove the "last" bound

job.last_at = Rufus::Scheduler.parse('2029-12-12')
  # set the last bound

times: nb of times (before auto-unscheduling)

One can tell how many times a repeat job (CronJob or EveryJob) is to execute before unscheduling by itself.

scheduler.every '2d', times: 10 do
  # ... do something every two days, but not more than 10 times
end

scheduler.cron '0 23 * * *', times: 31 do
  # ... do something every day at 23:00 but do it no more than 31 times
end

It's OK to assign nil to :times to make sure the repeat job is not limited. It's useful when the :times is determined at scheduling time.

scheduler.cron '0 23 * * *', times: (nolimit ? nil : 10) do
  # ...
end

The value set by :times is accessible in the job. It can be modified anytime.

job =
  scheduler.cron '0 23 * * *' do
    # ...
  end

# later on...

job.times = 10
  # 10 days and it will be over

Job methods

When calling a schedule method, the id (String) of the job is returned. Longer schedule methods return Job instances directly. Calling the shorter schedule methods with the job: true also returns Job instances instead of Job ids (Strings).

  require 'rufus-scheduler'

  scheduler = Rufus::Scheduler.new

  job_id =
    scheduler.in '10d' do
      # ...
    end

  job =
    scheduler.schedule_in '1w' do
      # ...
    end

  job =
    scheduler.in '1w', job: true do
      # ...
    end

Those Job instances have a few interesting methods / properties:

id, job_id

Returns the job id.

job = scheduler.schedule_in('10d') do; end
job.id
  # => "in_1374072446.8923042_0.0_0"

scheduler

Returns the scheduler instance itself.

opts

Returns the options passed at the Job creation.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.opts
  # => { :tag => 'hello' }

original

Returns the original schedule.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.original
  # => '10d'

callable, handler

callable() returns the scheduled block (or the call method of the callable object passed in lieu of a block)

handler() returns nil if a block was scheduled and the instance scheduled otherwise.

# when passing a block

job =
  scheduler.schedule_in('10d') do
    # ...
  end

job.handler
  # => nil
job.callable
  # => #<Proc:0x00000001dc6f58@/home/jmettraux/whatever.rb:115>

and

# when passing something else than a block

class MyHandler
  attr_reader :counter
  def initialize
    @counter = 0
  end
  def call(job, time)
    @counter = @counter + 1
  end
end

job = scheduler.schedule_in('10d', MyHandler.new)

job.handler
  # => #<Method: MyHandler#call>
job.callable
  # => #<MyHandler:0x0000000163ae88 @counter=0>

source_location

Added to rufus-scheduler 3.8.0.

Returns the array [ 'path/to/file.rb', 123 ] like Proc#source_location does.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

job = scheduler.schedule_every('2h') { p Time.now }

p job.source_location
  # ==> [ '/home/jmettraux/rufus-scheduler/test.rb', 6 ]

scheduled_at

Returns the Time instance when the job got created.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.scheduled_at
  # => 2013-07-17 23:48:54 +0900

last_time

Returns the last time the job triggered (is usually nil for AtJob and InJob).

job = scheduler.schedule_every('10s') do; end

job.scheduled_at
  # => 2013-07-17 23:48:54 +0900
job.last_time
  # => nil (since we've just scheduled it)

# after 10 seconds

job.scheduled_at
  # => 2013-07-17 23:48:54 +0900 (same as above)
job.last_time
  # => 2013-07-17 23:49:04 +0900

previous_time

Returns the previous #next_time

scheduler.every('10s') do |job|
  puts "job scheduled for #{job.previous_time} triggered at #{Time.now}"
  puts "next time will be around #{job.next_time}"
  puts "."
end

last_work_time, mean_work_time

The job keeps track of how long its work was in the last_work_time attribute. For a one time job (in, at) it's probably not very useful.

The attribute mean_work_time contains a computed mean work time. It's recomputed after every run (if it's a repeat job).

next_times(n)

Returns an array of EtOrbi::EoTime instances (Time instances with a designated time zone), listing the n next occurrences for this job.

Please note that for "interval" jobs, a mean work time is computed each time and it's used by this #next_times(n) method to approximate the next times beyond the immediate next time.

unschedule

Unschedule the job, preventing it from firing again and removing it from the schedule. This doesn't prevent a running thread for this job to run until its end.

threads

Returns the list of threads currently "hosting" runs of this Job instance.

kill

Interrupts all the work threads currently running for this job instance. They discard their work and are free for their next run (of whatever job).

Note: this doesn't unschedule the Job instance.

Note: if the job is pooled for another run, a free work thread will probably pick up that next run and the job will appear as running again. You'd have to unschedule and kill to make sure the job doesn't run again.

running?

Returns true if there is at least one running Thread hosting a run of this Job instance.

scheduled?

Returns true if the job is scheduled (is due to trigger). For repeat jobs it should return true until the job gets unscheduled. "at" and "in" jobs will respond with false as soon as they start running (execution triggered).

pause, resume, paused?, paused_at

These four methods are only available to CronJob, EveryJob and IntervalJob instances. One can pause or resume such jobs thanks to these methods.

job =
  scheduler.schedule_every('10s') do
    # ...
  end

job.pause
  # => 2013-07-20 01:22:22 +0900
job.paused?
  # => true
job.paused_at
  # => 2013-07-20 01:22:22 +0900

job.resume
  # => nil

tags

Returns the list of tags attached to this Job instance.

By default, returns an empty array.

job = scheduler.schedule_in('10d') do; end
job.tags
  # => []

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.tags
  # => [ 'hello' ]

[]=, [], key?, has_key?, keys, values, and entries

Threads have thread-local variables, similarly Rufus-scheduler jobs have job-local variables. Those are more like a dict with thread-safe access.

job =
  @scheduler.schedule_every '1s' do |job|
    job[:timestamp] = Time.now.to_f
    job[:counter] ||= 0
    job[:counter] += 1
  end

sleep 3.6

job[:counter]
  # => 3

job.key?(:timestamp) # => true
job.has_key?(:timestamp) # => true
job.keys # => [ :timestamp, :counter ]

Locals can be set at schedule time:

job0 =
  @scheduler.schedule_cron '*/15 12 * * *', locals: { a: 0 } do
    # ...
  end
job1 =
  @scheduler.schedule_cron '*/15 13 * * *', l: { a: 1 } do
    # ...
  end

One can fetch the Hash directly with Job#locals. Of course, direct manipulation is not thread-safe.

job.locals.entries do |k, v|
  p "#{k}: #{v}"
end

call

Job instances have a #call method. It simply calls the scheduled block or callable immediately.

job =
  @scheduler.schedule_every '10m' do |job|
    # ...
  end

job.call

Warning: the Scheduler#on_error handler is not involved. Error handling is the responsibility of the caller.

If the call has to be rescued by the error handler of the scheduler, call(true) might help:

require 'rufus-scheduler'

s = Rufus::Scheduler.new

def s.on_error(job, err)
  if job
    p [ 'error in scheduled job', job.class, job.original, err.message ]
  else
    p [ 'error while scheduling', err.message ]
  end
rescue
  p $!
end

job =
  s.schedule_in('1d') do
    fail 'again'
  end

job.call(true)
  #
  # true lets the error_handler deal with error in the job call

AtJob and InJob methods

time

Returns when the job will trigger (hopefully).

next_time

An alias for time.

EveryJob, IntervalJob and CronJob methods

next_time

Returns the next time the job will trigger (hopefully).

count

Returns how many times the job fired.

EveryJob methods

frequency

It returns the scheduling frequency. For a job scheduled "every 20s", it's 20.

It's used to determine if the job frequency is higher than the scheduler frequency (it raises an ArgumentError if that is the case).

IntervalJob methods

interval

Returns the interval scheduled between each execution of the job.

Every jobs use a time duration between each start of their execution, while interval jobs use a time duration between the end of an execution and the start of the next.

CronJob methods

brute_frequency

An expensive method to run, it's brute. It caches its results. By default it runs for 2017 (a non leap-year).

  require 'rufus-scheduler'

  Rufus::Scheduler.parse('* * * * *').brute_frequency
    #
    # => #<Fugit::Cron::Frequency:0x00007fdf4520c5e8
    #      @span=31536000.0, @delta_min=60, @delta_max=60,
    #      @occurrences=525600, @span_years=1.0, @yearly_occurrences=525600.0>
      #
      # Occurs 525600 times in a span of 1 year (2017) and 1 day.
      # There are least 60 seconds between "triggers" and at most 60 seconds.

  Rufus::Scheduler.parse('0 12 * * *').brute_frequency
    # => #<Fugit::Cron::Frequency:0x00007fdf451ec6d0
    #      @span=31536000.0, @delta_min=86400, @delta_max=86400,
    #      @occurrences=365, @span_years=1.0, @yearly_occurrences=365.0>
  Rufus::Scheduler.parse('0 12 * * *').brute_frequency.to_debug_s
    # => "dmin: 1D, dmax: 1D, ocs: 365, spn: 52W1D, spnys: 1, yocs: 365"
      #
      # 365 occurrences, at most 1 day between each, at least 1 day.

The CronJob#frequency method found in rufus-scheduler < 3.5 has been retired.

looking up jobs

Scheduler#job(job_id)

The scheduler #job(job_id) method can be used to look up Job instances.

  require 'rufus-scheduler'

  scheduler = Rufus::Scheduler.new

  job_id =
    scheduler.in '10d' do
      # ...
    end

  # later on...

  job = scheduler.job(job_id)

Scheduler #jobs #at_jobs #in_jobs #every_jobs #interval_jobs and #cron_jobs

Are methods for looking up lists of scheduled Job instances.

Here is an example:

  #
  # let's unschedule all the at jobs

  scheduler.at_jobs.each(&:unschedule)

Scheduler#jobs(tag: / tags: x)

When scheduling a job, one can specify one or more tags attached to the job. These can be used to look up the job later on.

  scheduler.in '10d', tag: 'main_process' do
    # ...
  end
  scheduler.in '10d', tags: [ 'main_process', 'side_dish' ] do
    # ...
  end

  # ...

  jobs = scheduler.jobs(tag: 'main_process')
    # find all the jobs with the 'main_process' tag

  jobs = scheduler.jobs(tags: [ 'main_process', 'side_dish' ]
    # find all the jobs with the 'main_process' AND 'side_dish' tags

Scheduler#running_jobs

Returns the list of Job instance that have currently running instances.

Whereas other "_jobs" method scan the scheduled job list, this method scans the thread list to find the job. It thus comprises jobs that are running but are not scheduled anymore (that happens for at and in jobs).

misc Scheduler methods

Scheduler#unschedule(job_or_job_id)

Unschedule a job given directly or by its id.

Scheduler#shutdown

Shuts down the scheduler, ceases any scheduler/triggering activity.

Scheduler#shutdown(:wait)

Shuts down the scheduler, waits (blocks) until all the jobs cease running.

Scheduler#shutdown(wait: n)

Shuts down the scheduler, waits (blocks) at most n seconds until all the jobs cease running. (Jobs are killed after n seconds have elapsed).

Scheduler#shutdown(:kill)

Kills all the job (threads) and then shuts the scheduler down. Radical.

Scheduler#down?

Returns true if the scheduler has been shut down.

Scheduler#started_at

Returns the Time instance at which the scheduler got started.

Scheduler #uptime / #uptime_s

Returns since the count of seconds for which the scheduler has been running.

#uptime_s returns this count in a String easier to grasp for humans, like "3d12m45s123".

Scheduler#join

Lets the current thread join the scheduling thread in rufus-scheduler. The thread comes back when the scheduler gets shut down.

#join is mostly used in standalone scheduling script (or tiny one file examples). Calling #join from a web application initializer will probably hijack the main thread and prevent the web application from being served. Do not put a #join in such a web application initializer file.

Scheduler#threads

Returns all the threads associated with the scheduler, including the scheduler thread itself.

Scheduler#work_threads(query=:all/:active/:vacant)

Lists the work threads associated with the scheduler. The query option defaults to :all.

  • :all : all the work threads
  • :active : all the work threads currently running a Job
  • :vacant : all the work threads currently not running a Job

Note that the main schedule thread will be returned if it is currently running a Job (ie one of those blocking: true jobs).

Scheduler#scheduled?(job_or_job_id)

Returns true if the arg is a currently scheduled job (see Job#scheduled?).

Scheduler#occurrences(time0, time1)

Returns a hash { job => [ t0, t1, ... ] } mapping jobs to their potential trigger time within the [ time0, time1 ] span.

Please note that, for interval jobs, the #mean_work_time is used, so the result is only a prediction.

Scheduler#timeline(time0, time1)

Like #occurrences but returns a list [ [ t0, job0 ], [ t1, job1 ], ... ] of time + job pairs.

dealing with job errors

The easy, job-granular way of dealing with errors is to rescue and deal with them immediately. The two next sections show examples. Skip them for explanations on how to deal with errors at the scheduler level.

block jobs

As said, jobs could take care of their errors themselves.

scheduler.every '10m' do
  begin
    # do something that might fail...
  rescue => e
    $stderr.puts '-' * 80
    $stderr.puts e.message
    $stderr.puts e.stacktrace
    $stderr.puts '-' * 80
  end
end

callable jobs

Jobs are not only shrunk to blocks, here is how the above would look like with a dedicated class.

scheduler.every '10m', Class.new do
  def call(job)
    # do something that might fail...
  rescue => e
    $stderr.puts '-' * 80
    $stderr.puts e.message
    $stderr.puts e.stacktrace
    $stderr.puts '-' * 80
  end
end

TODO: talk about callable#on_error (if implemented)

(see scheduling handler instances and scheduling handler classes for more about those "callable jobs")

Rufus::Scheduler#stderr=

By default, rufus-scheduler intercepts all errors (that inherit from StandardError) and dumps abundant details to $stderr.

If, for example, you'd like to divert that flow to another file (descriptor), you can reassign $stderr for the current Ruby process

$stderr = File.open('/var/log/myapplication.log', 'ab')

or, you can limit that reassignement to the scheduler itself

scheduler.stderr = File.open('/var/log/myapplication.log', 'ab')

Rufus::Scheduler#on_error(job, error)

We've just seen that, by default, rufus-scheduler dumps error information to $stderr. If one needs to completely change what happens in case of error, it's OK to overwrite #on_error

def scheduler.on_error(job, error)

  Logger.warn("intercepted error in #{job.id}: #{error.message}")
end

On Rails, the on_error method redefinition might look like:

def scheduler.on_error(job, error)

  Rails.logger.error(
    "err#{error.object_id} rufus-scheduler intercepted #{error.inspect}" +
    " in job #{job.inspect}")
  error.backtrace.each_with_index do |line, i|
    Rails.logger.error(
      "err#{error.object_id} #{i}: #{line}")
  end
end

Callbacks

Rufus::Scheduler #on_pre_trigger and #on_post_trigger callbacks

One can bind callbacks before and after jobs trigger:

s = Rufus::Scheduler.new

def s.on_pre_trigger(job, trigger_time)
  puts "triggering job #{job.id}..."
end

def s.on_post_trigger(job, trigger_time)
  puts "triggered job #{job.id}."
end

s.every '1s' do
  # ...
end

The trigger_time is the time at which the job triggers. It might be a bit before Time.now.

Warning: these two callbacks are executed in the scheduler thread, not in the work threads (the threads where the job execution really happens).

Rufus::Scheduler#around_trigger

One can create an around callback which will wrap a job:

def s.around_trigger(job)
  t = Time.now
  puts "Starting job #{job.id}..."
  yield
  puts "job #{job.id} finished in #{Time.now-t} seconds."
end

The around callback is executed in the thread.

Rufus::Scheduler#on_pre_trigger as a guard

Returning false in on_pre_trigger will prevent the job from triggering. Returning anything else (nil, -1, true, ...) will let the job trigger.

Note: your business logic should go in the scheduled block itself (or the scheduled instance). Don't put business logic in on_pre_trigger. Return false for admin reasons (backend down, etc), not for business reasons that are tied to the job itself.

def s.on_pre_trigger(job, trigger_time)

  return false if Backend.down?

  puts "triggering job #{job.id}..."
end

Rufus::Scheduler.new options

:frequency

By default, rufus-scheduler sleeps 0.300 second between every step. At each step it checks for jobs to trigger and so on.

The :frequency option lets you change that 0.300 second to something else.

scheduler = Rufus::Scheduler.new(frequency: 5)

It's OK to use a time string to specify the frequency.

scheduler = Rufus::Scheduler.new(frequency: '2h10m')
  # this scheduler will sleep 2 hours and 10 minutes between every "step"

Use with care.

lockfile: "mylockfile.txt"

This feature only works on OSes that support the flock (man 2 flock) call.

Starting the scheduler with lockfile: '.rufus-scheduler.lock' will make the scheduler attempt to create and lock the file .rufus-scheduler.lock in the current working directory. If that fails, the scheduler will not start.

The idea is to guarantee only one scheduler (in a group of schedulers sharing the same lockfile) is running.

This is useful in environments where the Ruby process holding the scheduler gets started multiple times.

If the lockfile mechanism here is not sufficient, you can plug your custom mechanism. It's explained in advanced lock schemes below.

:scheduler_lock

(since rufus-scheduler 3.0.9)

The scheduler lock is an object that responds to #lock and #unlock. The scheduler calls #lock when starting up. If the answer is false, the scheduler stops its initialization work and won't schedule anything.

Here is a sample of a scheduler lock that only lets the scheduler on host "coffee.example.com" start:

class HostLock
  def initialize(lock_name)
    @lock_name = lock_name
  end
  def lock
    @lock_name == `hostname -f`.strip
  end
  def unlock
    true
  end
end

scheduler =
  Rufus::Scheduler.new(scheduler_lock: HostLock.new('coffee.example.com'))

By default, the scheduler_lock is an instance of Rufus::Scheduler::NullLock, with a #lock that returns true.

:trigger_lock

(since rufus-scheduler 3.0.9)

The trigger lock in an object that responds to #lock. The scheduler calls that method on the job lock right before triggering any job. If the answer is false, the trigger doesn't happen, the job is not done (at least not in this scheduler).

Here is a (stupid) PingLock example, it'll only trigger if an "other host" is not responding to ping. Do not use that in production, you don't want to fork a ping process for each trigger attempt...

class PingLock
  def initialize(other_host)
    @other_host = other_host
  end
  def lock
    ! system("ping -c 1 #{@other_host}")
  end
end

scheduler =
  Rufus::Scheduler.new(trigger_lock: PingLock.new('main.example.com'))

By default, the trigger_lock is an instance of Rufus::Scheduler::NullLock, with a #lock that always returns true.

As explained in advanced lock schemes, another way to tune that behaviour is by overriding the scheduler's #confirm_lock method. (You could also do that with an #on_pre_trigger callback).

:max_work_threads

In rufus-scheduler 2.x, by default, each job triggering received its own, brand new, thread of execution. In rufus-scheduler 3.x, execution happens in a pooled work thread. The max work thread count (the pool size) defaults to 28.

One can set this maximum value when starting the scheduler.

scheduler = Rufus::Scheduler.new(max_work_threads: 77)

It's OK to increase the :max_work_threads of a running scheduler.

scheduler.max_work_threads += 10

Rufus::Scheduler.singleton

Do not want to store a reference to your rufus-scheduler instance? Then Rufus::Scheduler.singleton can help, it returns a singleton instance of the scheduler, initialized the first time this class method is called.

Rufus::Scheduler.singleton.every '10s' { puts "hello, world!" }

It's OK to pass initialization arguments (like :frequency or :max_work_threads) but they will only be taken into account the first time .singleton is called.

Rufus::Scheduler.singleton(max_work_threads: 77)
Rufus::Scheduler.singleton(max_work_threads: 277) # no effect

The .s is a shortcut for .singleton.

Rufus::Scheduler.s.every '10s' { puts "hello, world!" }

advanced lock schemes

As seen above, rufus-scheduler proposes the :lockfile system out of the box. If in a group of schedulers only one is supposed to run, the lockfile mechanism prevents schedulers that have not set/created the lockfile from running.

There are situations where this is not sufficient.

By overriding #lock and #unlock, one can customize how schedulers lock.

This example was provided by Eric Lindvall:

class ZookeptScheduler < Rufus::Scheduler

  def initialize(zookeeper, opts={})
    @zk = zookeeper
    super(opts)
  end

  def lock
    @zk_locker = @zk.exclusive_locker('scheduler')
    @zk_locker.lock # returns true if the lock was acquired, false else
  end

  def unlock
    @zk_locker.unlock
  end

  def confirm_lock
    return false if down?
    @zk_locker.assert!
  rescue ZK::Exceptions::LockAssertionFailedError => e
    # we've lost the lock, shutdown (and return false to at least prevent
    # this job from triggering
    shutdown
    false
  end
end

This uses a zookeeper to make sure only one scheduler in a group of distributed schedulers runs.

The methods #lock and #unlock are overridden and #confirm_lock is provided, to make sure that the lock is still valid.

The #confirm_lock method is called right before a job triggers (if it is provided). The more generic callback #on_pre_trigger is called right after #confirm_lock.

:scheduler_lock and :trigger_lock

(introduced in rufus-scheduler 3.0.9).

Another way of prodiving #lock, #unlock and #confirm_lock to a rufus-scheduler is by using the :scheduler_lock and :trigger_lock options.

See :trigger_lock and :scheduler_lock.

The scheduler lock may be used to prevent a scheduler from starting, while a trigger lock prevents individual jobs from triggering (the scheduler goes on scheduling).

One has to be careful with what goes in #confirm_lock or in a trigger lock, as it gets called before each trigger.

Warning: you may think you're heading towards "high availability" by using a trigger lock and having lots of schedulers at hand. It may be so if you limit yourself to scheduling the same set of jobs at scheduler startup. But if you add schedules at runtime, they stay local to their scheduler. There is no magic that propagates the jobs to all the schedulers in your pack.

parsing cronlines and time strings

(Please note that fugit does the heavy-lifting parsing work for rufus-scheduler).

Rufus::Scheduler provides a class method .parse to parse time durations and cron strings. It's what it's using when receiving schedules. One can use it directly (no need to instantiate a Scheduler).

require 'rufus-scheduler'

Rufus::Scheduler.parse('1w2d')
  # => 777600.0
Rufus::Scheduler.parse('1.0w1.0d')
  # => 777600.0

Rufus::Scheduler.parse('Sun Nov 18 16:01:00 2012').strftime('%c')
  # => 'Sun Nov 18 16:01:00 2012'

Rufus::Scheduler.parse('Sun Nov 18 16:01:00 2012 Europe/Berlin').strftime('%c %z')
  # => 'Sun Nov 18 15:01:00 2012 +0000'

Rufus::Scheduler.parse(0.1)
  # => 0.1

Rufus::Scheduler.parse('* * * * *')
  # => #<Fugit::Cron:0x00007fb7a3045508
  #      @original="* * * * *", @cron_s=nil,
  #      @seconds=[0], @minutes=nil, @hours=nil, @monthdays=nil, @months=nil,
  #      @weekdays=nil, @zone=nil, @timezone=nil>

It returns a number when the input is a duration and a Fugit::Cron instance when the input is a cron string.

It will raise an ArgumentError if it can't parse the input.

Beyond .parse, there are also .parse_cron and .parse_duration, for finer granularity.

There is an interesting helper method named .to_duration_hash:

require 'rufus-scheduler'

Rufus::Scheduler.to_duration_hash(60)
  # => { :m => 1 }
Rufus::Scheduler.to_duration_hash(62.127)
  # => { :m => 1, :s => 2, :ms => 127 }

Rufus::Scheduler.to_duration_hash(62.127, drop_seconds: true)
  # => { :m => 1 }

cronline notations specific to rufus-scheduler

first Monday, last Sunday et al

To schedule something at noon every first Monday of the month:

scheduler.cron('00 12 * * mon#1') do
  # ...
end

To schedule something at noon the last Sunday of every month:

scheduler.cron('00 12 * * sun#-1') do
  # ...
end
#
# OR
#
scheduler.cron('00 12 * * sun#L') do
  # ...
end

Such cronlines can be tested with scripts like:

require 'rufus-scheduler'

Time.now
  # => 2013-10-26 07:07:08 +0900
Rufus::Scheduler.parse('* * * * mon#1').next_time.to_s
  # => 2013-11-04 00:00:00 +0900

L (last day of month)

L can be used in the "day" slot:

In this example, the cronline is supposed to trigger every last day of the month at noon:

require 'rufus-scheduler'
Time.now
  # => 2013-10-26 07:22:09 +0900
Rufus::Scheduler.parse('00 12 L * *').next_time.to_s
  # => 2013-10-31 12:00:00 +0900

negative day (x days before the end of the month)

It's OK to pass negative values in the "day" slot:

scheduler.cron '0 0 -5 * *' do
  # do it at 00h00 5 days before the end of the month...
end

Negative ranges (-10--5-: 10 days before the end of the month to 5 days before the end of the month) are OK, but mixed positive / negative ranges will raise an ArgumentError.

Negative ranges with increments (-10---2/2) are accepted as well.

Descending day ranges are not accepted (10-8 or -8--10 for example).

a note about timezones

Cron schedules and at schedules support the specification of a timezone.

scheduler.cron '0 22 * * 1-5 America/Chicago' do
  # the job...
end

scheduler.at '2013-12-12 14:00 Pacific/Samoa' do
  puts "it's tea time!"
end

# or even

Rufus::Scheduler.parse("2013-12-12 14:00 Pacific/Saipan")
  # => #<Rufus::Scheduler::ZoTime:0x007fb424abf4e8 @seconds=1386820800.0, @zone=#<TZInfo::DataTimezone: Pacific/Saipan>, @time=nil>

I get "zotime.rb:41:in `initialize': cannot determine timezone from nil"

For when you see an error like:

rufus-scheduler/lib/rufus/scheduler/zotime.rb:41:
  in `initialize':
    cannot determine timezone from nil (etz:nil,tnz:"中国标准时间",tzid:nil)
      (ArgumentError)
    from rufus-scheduler/lib/rufus/scheduler/zotime.rb:198:in `new'
    from rufus-scheduler/lib/rufus/scheduler/zotime.rb:198:in `now'
    from rufus-scheduler/lib/rufus/scheduler.rb:561:in `start'
    ...

It may happen on Windows or on systems that poorly hint to Ruby which timezone to use. It should be solved by setting explicitly the ENV['TZ'] before the scheduler instantiation:

ENV['TZ'] = 'Asia/Shanghai'
scheduler = Rufus::Scheduler.new
scheduler.every '2s' do
  puts "#{Time.now} Hello #{ENV['TZ']}!"
end

On Rails you might want to try with:

ENV['TZ'] = Time.zone.name # Rails only
scheduler = Rufus::Scheduler.new
scheduler.every '2s' do
  puts "#{Time.now} Hello #{ENV['TZ']}!"
end

(Hat tip to Alexander in gh-230)

Rails sets its timezone under config/application.rb.

Rufus-Scheduler 3.3.3 detects the presence of Rails and uses its timezone setting (tested with Rails 4), so setting ENV['TZ'] should not be necessary.

The value can be determined thanks to https://en.wikipedia.org/wiki/List_of_tz_database_time_zones.

Use a "continent/city" identifier (for example "Asia/Shanghai"). Do not use an abbreviation (not "CST") and do not use a local time zone name (not "中国标准时间" nor "Eastern Standard Time" which, for instance, points to a time zone in America and to another one in Australia...).

If the error persists (and especially on Windows), try to add the tzinfo-data to your Gemfile, as in:

gem 'tzinfo-data'

or by manually requiring it before requiring rufus-scheduler (if you don't use Bundler):

require 'tzinfo/data'
require 'rufus-scheduler'

so Rails?

Yes, I know, all of the above is boring and you're only looking for a snippet to paste in your Ruby-on-Rails application to schedule...

Here is an example initializer:

#
# config/initializers/scheduler.rb

require 'rufus-scheduler'

# Let's use the rufus-scheduler singleton
#
s = Rufus::Scheduler.singleton


# Stupid recurrent task...
#
s.every '1m' do

  Rails.logger.info "hello, it's #{Time.now}"
  Rails.logger.flush
end

And now you tell me that this is good, but you want to schedule stuff from your controller.

Maybe:

class ScheController < ApplicationController

  # GET /sche/
  #
  def index

    job_id =
      Rufus::Scheduler.singleton.in '5s' do
        Rails.logger.info "time flies, it's now #{Time.now}"
      end

    render text: "scheduled job #{job_id}"
  end
end

The rufus-scheduler singleton is instantiated in the config/initializers/scheduler.rb file, it's then available throughout the webapp via Rufus::Scheduler.singleton.

Warning: this works well with single-process Ruby servers like Webrick and Thin. Using rufus-scheduler with Passenger or Unicorn requires a bit more knowledge and tuning, gently provided by a bit of googling and reading, see Faq above.

avoid scheduling when running the Ruby on Rails console

(Written in reply to gh-186)

If you don't want rufus-scheduler to trigger anything while running the Ruby on Rails console, running for tests/specs, or running from a Rake task, you can insert a conditional return statement before jobs are added to the scheduler instance:

#
# config/initializers/scheduler.rb

require 'rufus-scheduler'

return if defined?(Rails::Console) || Rails.env.test? || File.split($PROGRAM_NAME).last == 'rake'
  #
  # do not schedule when Rails is run from its console, for a test/spec, or
  # from a Rake task

# return if $PROGRAM_NAME.include?('spring')
  #
  # see https://github.com/jmettraux/rufus-scheduler/issues/186

s = Rufus::Scheduler.singleton

s.every '1m' do
  Rails.logger.info "hello, it's #{Time.now}"
  Rails.logger.flush
end

(Beware later version of Rails where Spring takes care pre-running the initializers. Running spring stop or disabling Spring might be necessary in some cases to see changes to initializers being taken into account.)

rails server -d

(Written in reply to https://github.com/jmettraux/rufus-scheduler/issues/165 )

There is the handy rails server -d that starts a development Rails as a daemon. The annoying thing is that the scheduler as seen above is started in the main process that then gets forked and daemonized. The rufus-scheduler thread (and any other thread) gets lost, no scheduling happens.

I avoid running -d in development mode and bother about daemonizing only for production deployment.

These are two well crafted articles on process daemonization, please read them:

If, anyway, you need something like rails server -d, why not try bundle exec unicorn -D instead? In my (limited) experience, it worked out of the box (well, had to add gem 'unicorn' to Gemfile first).

executor / reloader

You might benefit from wraping your scheduled code in the executor or reloader. Read more here: https://guides.rubyonrails.org/threading_and_code_execution.html

support

see getting help above.


Author: jmettraux
Source code: https://github.com/jmettraux/rufus-scheduler
License: MIT license

#ruby 

Earlene  Rowe

Earlene Rowe

1596343200

Top Vue Packages for Adding Charts, Unique IDs, Sliders & Scroll Lock

Vue.js is an easy to use web app framework that we can use to develop interactive front end apps.

In this article, we’ll look at the best packages for adding charts, unique IDs, sliders, and scroll lock.

vue-unique-id

vue-unique-id lets us add a unique ID to our Vue component.

To use it, we run:

npm i vue-unique-id

to install it.

Then we write:

main.js

import Vue from "vue";
import App from "./App.vue";
import UniqueId from "vue-unique-id";
Vue.use(UniqueId);
Vue.config.productionTip = false;
new Vue({
  render: h => h(App)
}).$mount("#app");

App.vue

<template>
  <div id="app"></div>
</template>

<script>
export default {
  created() {
    console.log(this.uid);
  }
};
</script>

We register the plugin and use the this.uid property to get the unique ID.

Also, we can get the ID with the $id method.

For instance, we can write:

<template>
  <div id="app"></div>
</template>

<script>
export default {
  created() {
    console.log(this.$id("foo"));
  }
};
</script>

to get an ID with the 'foo' suffix added to it.

VueVisible

VueVisible is a directive that lets us display something conditionally.

To use it, we run:

npm i vue-visible

to install it.

Then we use it by writing:

<template>
  <div id="app">
    <div v-visible="isVisible">I'm visible</div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isVisible: true
    };
  }
};
</script>

We just use the v-visible directive like the v-show directive to conditionally display something.

#javascript #software-development #programming #web-development #vue #vue.js

Luna  Mosciski

Luna Mosciski

1600583123

8 Popular Websites That Use The Vue.JS Framework

In this article, we are going to list out the most popular websites using Vue JS as their frontend framework.

Vue JS is one of those elite progressive JavaScript frameworks that has huge demand in the web development industry. Many popular websites are developed using Vue in their frontend development because of its imperative features.

This framework was created by Evan You and still it is maintained by his private team members. Vue is of course an open-source framework which is based on MVVM concept (Model-view view-Model) and used extensively in building sublime user-interfaces and also considered a prime choice for developing single-page heavy applications.

Released in February 2014, Vue JS has gained 64,828 stars on Github, making it very popular in recent times.

Evan used Angular JS on many operations while working for Google and integrated many features in Vue to cover the flaws of Angular.

“I figured, what if I could just extract the part that I really liked about Angular and build something really lightweight." - Evan You

#vuejs #vue #vue-with-laravel #vue-top-story #vue-3 #build-vue-frontend #vue-in-laravel #vue.js

Top VueJS App Development Company in USA

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Gordon  Matlala

Gordon Matlala

1667279100

Jekyll-spaceship: Jekyll Plugin for Astronauts

 🚀 Jekyll Spaceship 🚀 

Jekyll plugin for Astronauts.

Spaceship is a minimalistic, powerful and extremely customizable Jekyll plugin. It combines everything you may need for convenient work, without unnecessary complications, like a real spaceship.

Jekyll Spaceship Demo

💡 Tip: I hope you enjoy using this plugin. If you like this project, a little star for it is your way make a clear statement: My work is valued. I would appreciate your support! Thank you!

Requirements

  • Ruby >= 2.3.0

Installation

Add jekyll-spaceship plugin in your site's Gemfile, and run bundle install.

# If you have any plugins, put them here!
group :jekyll_plugins do
  gem 'jekyll-spaceship'
end

Or you better like to write in one line:

gem 'jekyll-spaceship', group: :jekyll_plugins

Add jekyll-spaceship to the plugins: section in your site's _config.yml.

plugins:
  - jekyll-spaceship

💡 Tip: Note that GitHub Pages runs in safe mode and only allows a set of whitelisted plugins. To use the gem in GitHub Pages, you need to build locally or use CI (e.g. travis, github workflow) and deploy to your gh-pages branch.

Additions for Unlimited GitHub Pages

  • Here is a GitHub Action named jekyll-deploy-action for Jekyll site deployment conveniently. 👍
  • Here is a Jekyll site using Travis to build and deploy to GitHub Pages for your references.

Configuration

This plugin runs with the following configuration options by default. Alternative settings for these options can be explicitly specified in the configuration file _config.yml.

# Where things are
jekyll-spaceship:
  # default enabled processors
  processors:
    - table-processor
    - mathjax-processor
    - plantuml-processor
    - mermaid-processor
    - polyfill-processor
    - media-processor
    - emoji-processor
    - element-processor
  mathjax-processor:
    src:
      - https://polyfill.io/v3/polyfill.min.js?features=es6
      - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
    config:
      tex:
        inlineMath:
          - ['$','$']
          - ['\(','\)']
        displayMath:
          - ['$$','$$']
          - ['\[','\]']
      svg:
        fontCache: 'global'
    optimize: # optimization on building stage to check and add mathjax scripts
      enabled: true # value `false` for adding to all pages
      include: []   # include patterns for math expressions checking (regexp)
      exclude: []   # exclude patterns for math expressions checking (regexp)
  plantuml-processor:
    mode: default  # mode value 'pre-fetch' for fetching image at building stage
    css:
      class: plantuml
    syntax:
      code: 'plantuml!'
      custom: ['@startuml', '@enduml']
    src: http://www.plantuml.com/plantuml/svg/
  mermaid-processor:
    mode: default  # mode value 'pre-fetch' for fetching image at building stage
    css:
      class: mermaid
    syntax:
      code: 'mermaid!'
      custom: ['@startmermaid', '@endmermaid']
    config:
      theme: default
    src: https://mermaid.ink/svg/
  media-processor:
    default:
      id: 'media-{id}'
      class: 'media'
      width: '100%'
      height: 350
      frameborder: 0
      style: 'max-width: 600px; outline: none;'
      allow: 'encrypted-media; picture-in-picture'
  emoji-processor:
    css:
      class: emoji
    src: https://github.githubassets.com/images/icons/emoji/

Usage

1. Table Usage

For now, these extended features are provided:

  • Cells spanning multiple columns
  • Cells spanning multiple rows
  • Cells text align separately
  • Table header not required
  • Grouped table header rows or data rows

Noted that GitHub filters out style property, so the example displays with the obsolete align property. But in actual this plugin outputs style property with text-align CSS attribute.

Rowspan and Colspan

^^ in a cell indicates it should be merged with the cell above.
This feature is contributed by pmccloghrylaing.

|              Stage | Direct Products | ATP Yields |
| -----------------: | --------------: | ---------: |
|         Glycolysis |          2 ATP              ||
| ^^                 |          2 NADH |   3--5 ATP |
| Pyruvaye oxidation |          2 NADH |      5 ATP |
|  Citric acid cycle |          2 ATP              ||
| ^^                 |          6 NADH |     15 ATP |
| ^^                 |          2 FADH |      3 ATP |
|                               30--32 ATP        |||

Code above would be parsed as:

StageDirect ProductsATP Yields
Glycolysis2 ATP
2 NADH3–5 ATP
Pyruvaye oxidation2 NADH5 ATP
Citric acid cycle2 ATP
6 NADH15 ATP
2 FADH23 ATP
30–32 ATP

Multiline

A backslash at end to join cell contents with the following lines.
This feature is contributed by Lucas-C.

| :    Easy Multiline   : |||
| :----- | :----- | :------ |
| Apple  | Banana | Orange  \
| Apple  | Banana | Orange  \
| Apple  | Banana | Orange
| Apple  | Banana | Orange  \
| Apple  | Banana | Orange  |
| Apple  | Banana | Orange  |

Code above would be parsed as:

Easy Multiline
Apple
Apple
Apple
Banana
Banana
Banana
Orange
Orange
Orange
Apple
Apple
Banana
Banana
Orange
Orange
AppleBananaOrange

Headerless

Table header can be eliminated.

|--|--|--|--|--|--|--|--|
|♜| |♝|♛|♚|♝|♞|♜|
| |♟|♟|♟| |♟|♟|♟|
|♟| |♞| | | | | |
| |♗| | |♟| | | |
| | | | |♙| | | |
| | | | | |♘| | |
|♙|♙|♙|♙| |♙|♙|♙|
|♖|♘|♗|♕|♔| | |♖|

Code above would be parsed as:

 
  
      
      
       
       
 
  

Cell Alignment

Markdown table syntax use colons ":" for forcing column alignment.
Therefore, here we also use it for forcing cell alignment.

Table cell can be set alignment separately.

| :        Fruits \|\| Food       : |||
| :--------- | :-------- | :--------  |
| Apple      | : Apple : | Apple      \
| Banana     |   Banana  | Banana     \
| Orange     |   Orange  | Orange     |
| :   Rowspan is 4    : || How's it?  |
|^^    A. Peach         ||   1. Fine :|
|^^    B. Orange        ||^^ 2. Bad   |
|^^    C. Banana        ||  It's OK!  |

Code above would be parsed as:

Fruits || Food
Apple
Banana
Orange
Apple
Banana
Orange
Apple
Banana
Orange
Rowspan is 4 
A. Peach 
B. Orange 
C. Banana
 
How's it?
1. Fine
2. Bad
It' OK!

Cell Markdown

Sometimes we may need some abundant content (e.g., mathjax, image, video) in Markdown table
Therefore, here we also make markown syntax possible inside a cell.

| :                   MathJax \|\| Image                 : |||
| :------------ | :-------- | :----------------------------- |
| Apple         | : Apple : | Apple                          \
| Banana        | Banana    | Banana                         \
| Orange        | Orange    | Orange                         |
| :     Rowspan is 4     : || :        How's it?           : |
| ^^     A. Peach          ||    1. ![example][cell-image]   |
| ^^     B. Orange         || ^^ 2. $I = \int \rho R^{2} dV$ |
| ^^     C. Banana         || **It's OK!**                   |

[cell-image]: https://jekyllrb.com/img/octojekyll.png "An exemplary image"

Code above would be parsed as:

MathJax || Image
Apple
Banana
Orange
Apple
Banana
Orange
Apple
Banana
Orange
Rowspan is 4 
A. Peach 
B. Orange 
C. Banana
 
How's it?
It' OK!

 

Cell Inline Attributes

This feature is very useful for custom cell such as using inline style. (e.g., background, color, font)
The idea and syntax comes from the Maruku package.

 

Following are some examples of attributes definitions (ALDs) and afterwards comes the syntax explanation:

{:ref-name: #id .cls1 .cls2}
{:second: ref-name #id-of-other title="hallo you"}
{:other: ref-name second}

An ALD line has the following structure:

  • a left brace, optionally preceded by up to three spaces,
  • followed by a colon, the id and another colon,
  • followed by attribute definitions (allowed characters are backslash-escaped closing braces or any character except a not escaped closing brace),
  • followed by a closing brace and optional spaces until the end of the line.

If there is more than one ALD with the same reference name, the attribute definitions of all the ALDs are processed like they are defined in one ALD.

An inline attribute list (IAL) is used to attach attributes to another element.
Here are some examples for span IALs:

{: #id .cls1 .cls2} <!-- #id <=> id="id", .cls1 .cls2 <=> class="cls1 cls2" -->
{: ref-name title="hallo you"}
{: ref-name class='.cls3' .cls4}

Here is an example for custom table cell with IAL:

{:color-style: style="background: black;"}
{:color-style: style="color: white;"}
{:text-style: style="font-weight: 800; text-decoration: underline;"}

|:             Here's an Inline Attribute Lists example                :||||
| ------- | ------------------ | -------------------- | ------------------ |
|:       :|:  <div style="color: red;"> &lt; Normal HTML Block > </div> :|||
| ^^      |   Red    {: .cls style="background: orange" }                |||
| ^^ IALs |   Green  {: #id style="background: green; color: white" }    |||
| ^^      |   Blue   {: style="background: blue; color: white" }         |||
| ^^      |   Black  {: color-style text-style }                         |||

Code above would be parsed as:

IALs

Additionally, here you can learn more details about IALs.

2. MathJax Usage

MathJax is an open-source JavaScript display engine for LaTeX, MathML, and AsciiMath notation that works in all modern browsers.

Some of the main features of MathJax include:

  • High-quality display of LaTeX, MathML, and AsciiMath notation in HTML pages
  • Supported in most browsers with no plug-ins, extra fonts, or special setup for the reader
  • Easy for authors, flexible for publishers, extensible for developers
  • Supports math accessibility, cut-and-paste interoperability, and other advanced functionality
  • Powerful API for integration with other web applications

2.1 Performance optimization

At building stage, the MathJax engine script will be added by automatically checking whether there is a math expression in the page, this feature can help you improve the page performance on loading speed.

2.2 How to use?

Put your math expression within $...$

$ a * b = c ^ b $
$ 2^{\frac{n-1}{3}} $
$ \int\_a^b f(x)\,dx. $

Code above would be parsed as:

MathJax Expression

3. PlantUML Usage

PlantUML is a component that allows to quickly write:

  • sequence diagram,
  • use case diagram,
  • class diagram,
  • activity diagram,
  • component diagram,
  • state diagram,
  • object diagram

There are two ways to create a diagram in your Jekyll blog page:

```plantuml!
Bob -> Alice : hello world
```

or

@startuml
Bob -> Alice : hello
@enduml

Code above would be parsed as:

PlantUML Diagram

4. Mermaid Usage

Mermaid is a Javascript based diagramming and charting tool. It generates diagrams flowcharts and more, using markdown-inspired text for ease and speed.

It allows to quickly write:

  • flow chart,
  • pie chart,
  • sequence diagram,
  • class diagram,
  • state diagram,
  • entity relationship diagram,
  • user journey,
  • gantt

There are two ways to create a diagram in your Jekyll blog page:

```mermaid!
pie title Pets adopted by volunteers
  "Dogs" : 386
  "Cats" : 85
  "Rats" : 35
```

or

@startmermaid
pie title Pets adopted by volunteers
  "Dogs" : 386
  "Cats" : 85
  "Rats" : 35
@endmermaid

Code above would be parsed as:

Mermaid Diagram

5. Media Usage

How often did you find yourself googling "How to embed a video/audio in markdown?"

While its not possible to embed a video/audio in markdown, the best and easiest way is to extract a frame from the video/audio. To add videos/audios to your markdown files easier I developped this tool for you, and it will parse the video/audio link inside the image block automatically.

For now, these media links parsing are provided:

  • Youtube
  • Vimeo
  • DailyMotion
  • Spotify
  • SoundCloud
  • General Video ( mp4 | avi | ogg | ogv | webm | 3gp | flv | mov ... )
  • General Audio ( mp3 | wav | ogg | mid | midi | aac | wma ... )

There are two ways to embed a video/audio in your Jekyll blog page:

Inline-style:

![]({media-link})

Reference-style:

![][{reference}]

[{reference}]: {media-link}

For configuring media attributes (e.g, width, height), just adding query string to the link as below:

![](https://www.youtube.com/watch?v=Ptk_1Dc2iPY?width=800&height=500)

![](https://www.dailymotion.com/video/x7tfyq3?width=100%&height=400&autoplay=1)

Youtube Usage

![](https://www.youtube.com/watch?v=Ptk_1Dc2iPY)

![](//www.youtube.com/watch?v=Ptk_1Dc2iPY?width=800&height=500)

Vimeo Usage

![](https://vimeo.com/263856289)

![](https://vimeo.com/263856289?width=500&height=320)

DailyMotion Usage

![](https://www.dailymotion.com/video/x7tfyq3)

![](https://dai.ly/x7tgcev?width=100%&height=400)

Spotify Usage

![](http://open.spotify.com/track/4Dg5moVCTqxAb7Wr8Dq2T5)

Spotify Podcast Usage

![](https://open.spotify.com/episode/31AxcwYdjsFtStds5JVWbT)

SoundCloud Usage

![](https://soundcloud.com/aviciiofficial/preview-avicii-vs-lenny)

General Video Usage

![](//www.html5rocks.com/en/tutorials/video/basics/devstories.webm)

![](//techslides.com/demos/sample-videos/small.ogv?allow=autoplay)

![](//techslides.com/demos/sample-videos/small.mp4?width=400)

General Audio Usage

![](//www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3)

![](//www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3?autoplay=1&loop=1)

6. Hybrid HTML with Markdown

As markdown is not only a lightweight markup language with plain-text-formatting syntax, but also an easy-to-read and easy-to-write plain text format, so writing a hybrid HTML with markdown is an awesome choice.

It's easy to write markdown inside HTML:

<script type="text/markdown">
# Hybrid HTML with Markdown is a not bad choice ^\_^

## Table Usage

| :        Fruits \|\| Food       : |||
| :--------- | :-------- | :--------  |
| Apple      | : Apple : | Apple      \
| Banana     |   Banana  | Banana     \
| Orange     |   Orange  | Orange     |
| :   Rowspan is 4    : || How's it?  |
|^^    A. Peach         ||   1. Fine :|
|^^    B. Orange        ||^^ 2. Bad   |
|^^    C. Banana        ||  It's OK!  |

## PlantUML Usage

@startuml
Bob -> Alice : hello
@enduml

## Video Usage

![](https://www.youtube.com/watch?v=Ptk_1Dc2iPY)
</script>

7. Markdown Polyfill

It allows us to polyfill features for extending markdown syntax.

For now, these polyfill features are provided:

  • Escape ordered list

7.1 Escape Ordered List

A backslash at begin to escape the ordered list.

Normal:

1. List item Apple.
3. List item Banana.
10. List item Cafe.

Escaped:

\1. List item Apple.
\3. List item Banana.
\10. List item Cafe.

Code above would be parsed as:

Normal:

1. List item Apple.
2. List item Banana.
3. List item Cafe.

Escaped:

1. List item Apple.
3. List item Banana.
10. List item Cafe.

8. Emoji Usage

GitHub-flavored emoji images and names would allow emojifying content such as: it's raining :cat:s and :dog:s!

Noted that emoji images are served from the GitHub.com CDN, with a base URL of https://github.githubassets.com, which results in emoji image URLs like https://github.githubassets.com/images/icons/emoji/unicode/1f604.png.

In any page or post, use emoji as you would normally, e.g.

I give this plugin two :+1:!

Code above would be parsed as:

I give this plugin two :+1:!

8.1 Emoji Customizing

If you'd like to serve emoji images locally, or use a custom emoji source, you can specify so in your _config.yml file:

jekyll-spaceship:
  emoji-processor:
    src: "/assets/images/emoji"

See the Gemoji documentation for generating image files.

9. Modifying Element Usage

It allows us to modify elements via CSS3 selectors. Through it you can easily modify the attributes of an element tag, replace the children nodes and so on, it's very flexible, but here is example usage for modifying a document:

# Here is a comprehensive example
jekyll-spaceship:
  element-processor:
    css:
      - a: '<h1>Test</h1>'                     # Replace all `a` tags (String Style)
      - ['a.link1', 'a.link2']:                # Replace all `a.link1`, `a.link2` tags (Hash Style)
          name: img                            # Replace element tag name
          props:                               # Replace element properties
            title: Good image                  # Add a title attribute
            src: ['(^.*$)', '\0?a=123']        # Add query string to src attribute by regex pattern
            style:                             # Add style attribute (Hash Style)
              color: red
              font-size: '1.2em'
          children:                            # Add children to the element
            -                                  # First empty for adding after the last child node
            - "<span>Google</span>"            # First child node (String Style)
            -                                  # Middle empty for wrapping the children nodes
            - name: span                       # Second child node (Hash Style)
              props:
                prop1: "1"                     # Custom property1
                prop2: "2"                     # Custom property2
                prop3: "3"                     # Custom property3
              children:                        # Add nested chidren nodes
                - "<span>Jekyll</span>"        # First child node (String Style)
                - name: span                   # Second child node (Hash Style)
                  props:                       # Add attributes to child node (Hash Style)
                    prop1: "a"
                    prop2: "b"
                    prop3: "c"
                  children: "<b>Yap!</b>"      # Add children nodes (String Style)
            -                                  # Last empty for adding before the first child node
      - a.link: '<a href="//t.com">Link</a>'   # Replace all `a.link` tags (String Style)
      - 'h1#title':                            # Replace `h1#title` tags (Hash Style)
          children: I'm a title!               # Replace inner html to new text

Example 1

Automatically adds a target="_blank" rel="noopener noreferrer" attribute to all external links in Jekyll's content.

jekyll-spaceship:
  element-processor:
    css:
      - a:                                     # Replace all `a` tags
          props:
            class: ['(^.*$)', '\0 ext-link']   # Add `ext-link` to class by regex pattern
            target: _blank                     # Replace `target` value to `_blank`
            rel: noopener noreferrer           # Replace `rel` value to `noopener noreferrer`

Example 2

Automatically adds loading="lazy" to img and iframe tags to natively load lazily. Browser support is growing. If a browser does not support the loading attribute, it will load the resource just like it would normally.

jekyll-spaceship:
  element-processor:
    css:
      - a:                                     # Replace all `a` tags
          props:                               #
            loading: lazy                      # Replace `loading` value to `lazy`

In case you want to prevent loading some images/iframes lazily, add loading="eager" to their tags. This might be useful to prevent flickering of images during navigation (e.g. the site's logo).

See the following examples to prevent lazy loading.

jekyll-spaceship:
  element-processor:
    css:
      - a:                                     # Replace all `a` tags
          props:                               #
            loading: eager                     # Replace `loading` value to `eager`

There are three options when using this method to lazy load images. Here are the supported values for the loading attribute:

  • auto: Default lazy-loading behavior of the browser, which is the same as not including the attribute.
  • lazy: Defer loading of the resource until it reaches a calculated distance from the viewport.
  • eager: Load the resource immediately, regardless of where it’s located on the page.

Credits

  • Jekyll - A blog-aware static site generator in Ruby.
  • MultiMarkdown - Lightweight markup processor to produce HTML, LaTeX, and more.
  • markdown-it-multimd-table - Multimarkdown table syntax plugin for markdown-it markdown parser.
  • jmoji - GitHub-flavored emoji plugin for Jekyll.
  • jekyll-target-blank - Automatically opens external links in a new browser for Jekyll Pages, Posts and Docs.
  • jekyll-loading-lazy - Automatically adds loading="lazy" to img and iframe tags to natively load lazily.
  • mermaid - Generation of diagram and flowchart from text in a similar manner as markdown.

Contributing

Issues and Pull Requests are greatly appreciated. If you've never contributed to an open source project before I'm more than happy to walk you through how to create a pull request.

You can start by opening an issue describing the problem that you're looking to resolve and we'll go from there.

Download Details:

Author: jeffreytse
Source Code: https://github.com/jeffreytse/jekyll-spaceship 
License: MIT license

#jekyll #music #emoji #html