JavaScript Message Boxes: alert(), confirm(), prompt()

In this Javascript tutorial, we will learn about JavaScript Message Boxes: alert(), confirm(), prompt(). explain what JavaScript is, why JavaScript is used, how to use JavaScript for validation, functions, and properties, and some easy functions that you can copy and paste into your code. This resource is entirely about JavaScript.

I have often observed that users put their problems on the CodeProject forum related to JavaScript. They don't know the exact use of JavaScript. Why should we use it? Where to define it?

Introduction

JavaScript is the most popular scripting language used in almost all browsers. The primary use of JavaScript is to validate user input. Besides that, JavaScript can be used for designing CSS, data manipulation, and more.

Including JavaScript to Page

JavaScript can be used with HTML, DHTML, XML, XHTML, ASP, JSP, ASPX, PHP, etc. JavaScript is defined in a separate block of HEAD. Let's see the following example; it will give you a clear idea.

<html>
     <head>
          <script language="JavaScript"> function CallMe(){alert("Yes..first POP up from javascript");return false;}</script>
     </head>

     <body> Welcome to javascript example!<input type="submit" id="sub1" onclick="return CallMe();"> </body>
</html>

Let's travel with the above code,

JavaScript defined under HEAD tag
We can write functions in JavaScript
the function is a reserved keyword
the alert is used for POP message
return false indicates the page should not submit to the server (means code execution will stop at that point)
We can call the JavaScript function using the onclick event
Like VBScript, we cannot change the caption of the POPup box in JavaScript

Using the Document Object

the document is the most commonly used object in JavaScript. We can collect any control from the page using a document as an object. Let's take an example.

Validating Page for empty textbox using document object

[now I am just giving an example through functions, you can call them on your page],

function ValidateME()
{
     if (document.getElementById("txtUserName").value == "")
     {
          alert("Please enter user Id rraannaammeett"); // Give alert to user
          document.getElementById("txtUserName").focus(); // Set focus on textbox
          return false;
     }
}

Change the forecolor/backcolor of the page using the document object

function ChangeME()
{
     document.bgColor = "red"; //change the backcolor to RED
     document.fgColor = "#338844"; //change the forecolor
}

Write on a page using the document object

function WriteME()
{
     document.write("I can write on page");
}

Access form controls using 'ALL' property (ALL property is a browser(IE) specific)

function GetControlValue()
{
     alert(document.all.txtUser.Value);
}

document object has numerous functions and properties. Here are some of them,

alinkColor - Specifies the color of activated links
domain - Gives domain name under which served you used for security purposes
title - Specifies the title of a document
cookie - A string containing the name/value pair of cookies in the document
FileSize - Return the file size of the current document
URL - A string that specifies the complete URL of the document
cookie - A string containing the name/value pair of cookies in the document

POP-UPs

The most famous part of JavaScript which the prompt user from the client side. Let's see how we can generate POP-UPs with some lines of code.

using alert

ALERT can be used to alert the user. A simple messagebox is accepted by all browsers.

Here is a small example

function giveAlert()
{
     alert("WOW ! this is alert");
     return false;
}

using confirm

CONFIRM can be used to confirm user decisions. A simple messagebox with OK and CANCEL buttons. This function returns a boolean value. Here is a small example,

function askFor()
{
     if (confirm("Are you sure rraannaammeett"))
          alert("Yes, i am sure rraannaammeett")
     else
          alert("No, i am not sure rraannaammeett")
}

using Prompt

This is used to accept input from users,

function EnterChoice()
{
     var reply = prompt("what is your name", "Enter your name")
     alert("HI" + reply);
}

Here var is the datatype in JavaScript like integer, string, and "reply" is the variable.

Event Handling

JavaScript supports several events; here we go for the most common/used events.

onClick

This event is supported mainly by all controls of the webform.

onClick handlers execute something only when users click buttons, links, checkboxes, radiobutton, etc.

<script>
     function callME()
     {
          alert("yes..OnClick called!")
     }
</script>
<form>
     <input type="button" value="Click Me" onclick="callME()">
</form>

onchange

This event is fired by the combo box while changing items in the combo list. Here is an example of how to get a selected item from the dropdownlist.

<script>
     function getItem()
     {
          alert("you select " + document.getElementById("idDDL").value)
     }
</script>
<form>
     <asp:Dropdownlist id="idDDL" runat="server" onchange="getItem()">
          <listItem>a<listItem>
     </asp:Dropdownlist>
</form>

onMouseover, onMouseout

These are exclusive events used when the mouse pointer is OVER and OUT from control.

<body>
     <a href="#" onMouseOver="alert('Hi,I am mouse over rraannaammeett!">Over Here!</a>
     <a href="#" onMouseOut="alert('Hin I am mouse out !')">Get Out Here!</a>
</body>

onUnLoad

This event calls JavaScript function while someone leaves the page, e.g., Giving a thanks message when the user leaves the page:

<body onunload="alert('Thank you for visiting rraannaammeett')">

onblur

This event is called when any user leaves Textbox; it is the same as a LostFocus event in Winforms. e.g., we can validate if the user has left the textbox empty.

function ValidateInt()
{
     if (document.getElementById("txtNum").value == "")
     {
          alert("You can not left number field empty");
          document.getElementById("txtNum").focus();
          return false;
     }
}

Working with Dates

Very few developers work with date in JavaScript. Here are some good examples to display today's date.

<HTML>

     <HEAD>
          <TITLE>Date using Javascript</TITLE>
     </HEAD>

     <BODY>
          <SCRIPT LANGUAGE="JavaScript">
          function CallMe()
          {
               var dt = new Date();
               alert("Todays date is " + dt);
          }
          </SCRIPT>
     </BODY>

</HTML>

Here are some functions that deal with date objects,

getTime() - Get the Number of milliseconds
getSeconds() - Get the Number of seconds (0-59)
getMinutes() - Get the Number of minutes (0-59)
getMinutes() - Get the Number of minutes (0-59)
getHours() - Get the Number of hours (0-23)
getDay() - Get Day of the week(0-6). 0 = Sunday, ... , 6 = Saturday
getDate() - Get Day of the month (0-31)
getMonth() - Get the Number of months (0-11)
getFullYear() - Get year range between(1970-9999)

Functions That Make Life Easy

Let's rock with the following functions that make life easy. You can call these functions on any event in your web application, like onclick, onblur, onchange, etc.

Check if the Textbox has a numeric value,

function checkInt()
{
     if (isNAN(document.getElementById("txtNum").value))
          alert("Please enter only numbers rraannaammeett");
}

*isNAN- The NaN property represents the "Not-a-Number" value. This method indicates that a value is not a legal number.

Evaluate expression

function checkInt()
{
     function evaluateME()
     {
          alert(eval(2 + 2));
     }
}

*eval- evaluates the expression and gets the output.

Display only the specified length of the string

function FormatMe()
{
     var exNum = new Number(3.141516254);
     alert(exNum.toPrecision(4));
} //Output : 3.141

*toPrecision()- This method formats a number to a specified length.

Alert box with a line break

We often need to display a message on different lines; here we go.

function disp_alert()
{
     alert("This is line 1 " + '\n' + "Yes, I am after line break rraannaammeett!");
}

*\n- Used to break lines.

Get how many char's entered in the textbox

function disp_char()
{
     alert("You have entered " + document.getElementById("txtUser").length() + " chars);
}

*length()- Used to get the length of the textbox.

Case Insensitive String Compare

function ValidateCases()
{
     var user1 = document.getElementById("txtUser").value;
     if (user1.toLowerCase() == "Welcome".toLowerCase())
          alert("Welcome matched");
     else alert("Access Denied!");
}

*toLowerCase()- Convert string to lowercase.

Split string with javascript

The following code is used to split string values with specified split char,

function SplitME()
{
     var myString = "str1/str2";
     var mySplitResult = myString.split("/");
     alert("The first element is " + mySplitResult[0]);
     alert("The second element is " + mySplitResult[1]);
}

*split()- This method splits the string with specified char.

Validate EMail address

The following code is used to validate an email address with Regular expressions,

function ValidateEmail()
{
     var pattern = "/^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$/";
     str = "test@gmail.com";
     alert(str.match(pattern));
     return false;
}

Showing/Hiding controls on a specific condition

A lot of times, we need to Hide/show control against a specific condition. Here is the function which will help us to TOGGLE the view of the state and pass the control id to the following function,

function Toggle(obj)
{
     var ctrlid = document.getElementById(obj);
     if (ctrlid.style.display != 'none')
          ctrlid.style.display = 'none';
     else
          ctrlid.style.display = '';
}

Prevent ENTER key on Textbox

Call the following function on the keypress event of Textbox.

function avoidEnter()
{
     if (event.keyCode == 13)
          return false;
}

Disabled RIGHT click using Javascript.

If you need to disable it right, click on Textbox / Document and use the following function:

function DisableRight()
{
     if (event.button == 2)
          return false;
}

* for textbox, call the above function on the OnCLIENTCLICK event * for the document, call the above function on the ONCLICK event of BODY

Debugging JavaScript with Visual Studio

You can debug the JavaScript functions by adding a debugger; keyword in the function. But before starting debugging, make sure that your debugging is enabled for the script in Internet Explorer. To check the setting, go to Internet Explorer --> Tools --> Internet Options --> Advanced Tab.

Original article source at: https://www.c-sharpcorner.com

#javascript

What is GEEK

Buddha Community

JavaScript Message Boxes: alert(), confirm(), prompt()

Steve Griffith

1598884238

alert, confirm, and prompt dialogs with JavaScript

https://www.youtube.com/watch?v=xXwSJGYqeIQ

How to create modal dialogs with the alert, confirm and prompt commands in JavaScript

#javascript #modal #alert #confirm #prompt #web-development

Milton Langworth

1659640560

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

It doesn't work...
I want a refund
Passenger and rufus-scheduler
Passenger and rufus-scheduler (2)
Passenger in-depth spawn methods
Passenger in-depth spawn methods (smart spawning)
The scheduler comes up when running the Rails console or a Rake task
The job triggers twice
I don't get any of this, I just want it to work in my Rails application
[I get "zotime.rb:41:in `initialize': cannot determine timezone from nil"](#i-get-zotimerb41in-initialize-cannot-determine-timezone-from-nil)

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

[]=, [], 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

Display Boxes

1624963019

Custom Printed Soap Boxes | Wholesale Soap Packaging | Custom Packaging Pro

You have a great quality product in your hand, and now you are thinking of ways to represent it to the customers in a most appealing way. Many brands are afraid of spending money on custom boxes without knowing that it is the most cost-effecting way with various benefits. When designed with proper planning and creativity, custom packaging can result in money. You shouldn’t mind spending a little more to save money in the long run. You may disagree with us, but investment in customization and personalization can open new doors of success for your business.

How Custom Boxes for Soap Are a Cost-Effective Solution?

From our kitchen cabinets to the big supermarkets, custom boxes are everywhere. We are surrounded by customization, even if it is about selling a small cosmetic product. When you deal in the soap market, you have to face a lot of competition. You can’t compete in the market with a strategy of using plain cardboard boxes. Gone are the days when you can use a simple packaging solution. Today is the age of customization, and you have to use custom Boxes for Soap. These are not only affordable but also look good on the shelves and provide an ultimate customer experience. Let’s take a deeper look at how custom packaging is a cost-effective solution with several benefits.

Helps To Reduce Shipping Prices

During this pandemic, the e-commerce industry has grown too fast, and every brand is selling its products online. One thing which is keeping the manufacturer is the high shipping price. But to make the right decision, you need to understand how shipping prices work. It is not only about the weight of the box; consider dimensional weight as well. Even if you are shipping a small item like soap, the box size can increase the shipping cost. So, the firsts step towards price reduction is using the box which is according to the product size and also light in weight.

Maximum Durability Ensures Protection

It is one of the most faced issues which brands face. Damaged and broken products always result in returns which ultimately means additional cost. No brand will ever want to face negative reviews and customer backlash. You can avoid it by using durable and sturdy boxes. When it comes to protection, corrugate and cardboard soap boxers can outclass every other solution. These two materials are quite affordable and readily available in the market. Once again, it is highly recommended to use the right box size to avoid damage and returns. You can also use other packaging materials for added protection.

Increase Your Visibility with Pillow Boxes

When it comes to increasing your visibility and exposure in retail stores, there is no better option other than custom containers. These come in a variety of shapes and styles, which increase the customer’s interest in your product. Custom Pillow Boxes are the right choice to present your soap products on the shelves. You can customize the pillow packaging further with other customization options like window patching, lamination, and gold stamping. Unique solutions always make customers take a closer look at the product, and most probably they will end up buying it.

Right Box Size Help to Save Big

We have mentioned it before, but it needs more repetition. A wrong size box will always cost you more. If you are thinking that you can end up saving by choosing the standard size boxes for all the products, you are wrong. It will cost you more in form of damaged products and returns. Moreover, the bigger will be the size of the box, the more you have to pay for shipping. So, always choose the right size, which suits the product dimensions, and don’t leave too much space in the containers. A bigger size box will also make you use the protective material.

Cardboard And Paperboard Are the Cheapest Options

If you still think that custom boxes are way out of your range, we have still so many options for you. Take a simple corrugate or cardboard box in white or any plain color, print your logo on it, and you have a custom box in your hand. Getting a custom solution for your soap products has never been so easy. Today is the age of minimalism, and you can take advantage of this trend. Use simple customization for a natural and minimal look. Cardboard and corrugated are the most affordable option when it comes to custom material.

Happy Customers Result in Repeat Business and Positive Reviews

When it comes to benefits with custom packaging, there are several benefits that you can get. From product protection to the customer experience, you will get everything with a custom solution. The biggest benefits of providing a personalized experience are repeat business and positive reviews from the customers. When you put your heart and effort into the customization, customers will reward you with positive feedback. A good review from the customers will attract more customers to your business. Satisfied customers will bring business with repeat business and higher brand recall.

Kraft Boxes for Display Improve Sustainability

When it comes to being sustainable, there is no better option than Kraft. Use Kraft packaging boxes to display your products on the shelves. It will attract more and more eco-conscious customers, which will ultimately result in boosted sales. It is not only a cheap option but offers 100% recyclability. The presentation and display of your product have a greater role to play in drawing the attraction. Using the same old-style packaging will not going to help you out. Think of something innovative and try using Kraft boxes for better results. Find a solution that is not unique but meets the customer’s needs.

When it comes to soap packaging, Kraft Boxes for Display are a perfect choice. These are not only cost-efficient but result in customer satisfaction, repeat business, and reduced shipping cost. Find a solution that meets your needs without breaking the budget.

#boxes for soap #boxes for pillow #boxes for display #soap boxes #pillow boxes #display boxes

Dylan North

1664864048

Add One or More Node Objects or String Objects in JavaScript

Learn how to add one or more node objects or string objects after the last child of the element inside a specific parent element using the append() method in JavaScript.

Append Element Node
Append Text Node
Append Multiple Elements At Once

1: Append Element Node

Let’s append an element node as a last child element of the parent element (section#box-wrapper).

Create an HTML file

<section id="box-wrapper">
  <div class="box">div <br>1</div>
  <div class="box">div <br>2</div>
  <div class="box">div <br>3</div>
  <div class="box">div <br>4</div>
</section>

Create a CSS file

@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');

html,
body {
  font-family: 'Roboto', cursive;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  font-size: 30px;
}
* {
  box-sizing:border-box;
  font-family:Arial;
  font-size:1em;
}

body {
  
  background:#ececec;
}

#box-wrapper {
  display:flex;
}

.box {
  display:flex;
  justify-content:center;
  align-items:center;
  width:100px;
  height:100px;
  background:#32bacf;
  margin:10px;
  text-align:center;
}

Create a JavaScript file

const boxWrapper = document.getElementById("box-wrapper");
const box = document.createElement("div");
box.innerHTML = 'div <br> 5';
box.style.backgroundColor = "orange";
box.classList.add("box");
boxWrapper.append(box);

Output

First, get a DOM reference of the parent element (section#box-wrapper) where we want to insert a new element to.

Call getElementById() method on the document object and pass the id (box-wrapper) as an argument to ti.

Then, create a div element by running the createElement() method on the document object.

It takes one argument, which is an HTML element that we want to create.

In this case: div

Assign it to a constant called box5.

Set the content, background color to the element using innerHTML, backgroundColor properties respectively.

Add the box class to the element by invoking the add() method on the classList object.

Finally, append the newly created child element to the parent element (section#box-wrapper).

This will insert the new element after the last child of the Element.

In this case, after the div 4.

2. Append Text Node/String

Create an HTML file

<section id="box-wrapper">
  <div class="box">div <br>1</div>
  <div class="box">div <br>2</div>
  <div class="box">div <br>3</div>
  <div class="box">div <br>4</div>
</section>

Create a CSS file

@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');

html,
body {
  font-family: 'Roboto', cursive;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  font-size: 30px;
}
* {
  box-sizing:border-box;
  font-family:Arial;
  font-size:1em;
}

body {
  
  background:#ececec;
}

#box-wrapper {
  display:flex;
}

.box {
  display:flex;
  justify-content:center;
  align-items:center;
  width:100px;
  height:100px;
  background:#32bacf;
  margin:10px;
  text-align:center;
}

Create a JavaScript file

const boxWrapper = document.getElementById("box-wrapper");

const text = document.createTextNode("Hey there!");
boxWrapper.append("Hey there!");

// boxWrapper.append("Hey there!");

Output

Using the append() method, you can also insert text node objects in addition to element node objects.

To do that, invoke createTextNode() method on the document object.

Pass the text as an argument to the createTextNode() method that you want to add to the DOM

In this case: Hey, there!

Assign it to a constant text.

Finally, insert the text after the last child of the element inside the parent element (boxWrapper) by calling the append() method on the boxWrapper object passing text as an argument to it.

3. Append Multiple Elements At Once

Next, let’s see how to add multiple elements at once using the append() method in JavaScript.

Create an HTML file

<section id="box-wrapper">
  <div class="box">div <br>1</div>
  <div class="box">div <br>2</div>
  <div class="box">div <br>3</div>
  <div class="box">div <br>4</div>
</section>

Create a CSS file

@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');

html,
body {
  font-family: 'Roboto', cursive;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  font-size: 30px;
}
* {
  box-sizing:border-box;
  font-family:Arial;
  font-size:1em;
}

body {
  
  background:#ececec;
}

#box-wrapper {
  display:flex;
}

.box {
  display:flex;
  justify-content:center;
  align-items:center;
  width:100px;
  height:100px;
  background:#32bacf;
  margin:10px;
  text-align:center;
}

Create a JavaScript file

const boxWrapper = document.getElementById("box-wrapper");

const box5 = document.createElement("div");
box5.innerHTML = 'div <br> 5';
box5.style.backgroundColor = "orange";
box5.classList.add("box");

const box6 = document.createElement("div");
box6.innerHTML = 'div <br> 6';
box6.style.backgroundColor = "orange";
box6.classList.add("box");

boxWrapper.append(box5, box6);

// for(let i = 5; i < 7; i++) {
//   const box = document.createElement("div");
//   box.innerHTML = 'div <br> ' + i;
//   box.classList.add("box");  
//   boxWrapper.append(box);
// }

Output

Let’s add two div elements after the last child of the element inside the parent element (section#box-wrapper) using the append() method.

Append both div element node objects by passing them as arguments of the append() method separated by a comma .

Happy Coding!!!

#html #css #javascript

Rahul Jangid

1622207074

What is JavaScript - Stackfindover - Blog

Who invented JavaScript, how it works, as we have given information about Programming language in our previous article ( What is PHP ), but today we will talk about what is JavaScript, why JavaScript is used The Answers to all such questions and much other information about JavaScript, you are going to get here today. Hope this information will work for you.

Who invented JavaScript?

JavaScript language was invented by Brendan Eich in 1995. JavaScript is inspired by Java Programming Language. The first name of JavaScript was Mocha which was named by Marc Andreessen, Marc Andreessen is the founder of Netscape and in the same year Mocha was renamed LiveScript, and later in December 1995, it was renamed JavaScript which is still in trend.

What is JavaScript?

JavaScript is a client-side scripting language used with HTML (Hypertext Markup Language). JavaScript is an Interpreted / Oriented language called JS in programming language JavaScript code can be run on any normal web browser. To run the code of JavaScript, we have to enable JavaScript of Web Browser. But some web browsers already have JavaScript enabled.

Today almost all websites are using it as web technology, mind is that there is maximum scope in JavaScript in the coming time, so if you want to become a programmer, then you can be very beneficial to learn JavaScript.

JavaScript Hello World Program

In JavaScript, ‘document.write‘ is used to represent a string on a browser.

<script type="text/javascript">
	document.write("Hello World!");
</script>

How to comment JavaScript code?

For single line comment in JavaScript we have to use // (double slashes)
For multiple line comments we have to use / * – – * /

<script type="text/javascript">

//single line comment

/* document.write("Hello"); */

</script>

Advantages and Disadvantages of JavaScript

#javascript #javascript code #javascript hello world #what is javascript #who invented javascript