Why We Use Refs in React Instead Of Id's

In this video, we can learn
what’s the exact problem we are going to face if we use ids to react.
How to resolve it with react refs.

For More Videos:
Essentials for Web Developers: https://www.youtube.com/watch?v=9uGuG2L08W0&list=PL20fyMtMStyGltl7wjgwSoKM_PmhB6J1v

Interview Questions: https://www.youtube.com/watch?v=Omu272bMBlk&list=PL20fyMtMStyEK2gggQurRKZMpbwgiMh-1

Best Practises & Common Mistakes: https://www.youtube.com/watch?v=Qtrl0OEzvMo&list=PL20fyMtMStyHL0uMGRLACViz8-04mhxcC

Reactjs beginner Playlist: https://www.youtube.com/watch?v=SkevBJhRV4M&list=PL20fyMtMStyFsrTQAjqc4QpkpCqrR3qN1


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Buddha Community

Why We Use Refs in React Instead Of Id's
Autumn  Blick

Autumn Blick


How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

  • Performance: It delivers optimal performance.
  • Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
  • UI design: React Native enables you to design simple and responsive UI for your mobile app.
  • 3rd party plugins: This framework supports 3rd party plugins.
  • Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

  • Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
  • Near-native user experience: React Native provides several native components, and these are platform agnostic.
  • The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

Chloe  Butler

Chloe Butler


Pdf2gerb: Perl Script Converts PDF Files to Gerber format


Perl script converts PDF files to Gerber format

Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.

The general workflow is as follows:

  1. Design the PCB using your favorite CAD or drawing software.
  2. Print the top and bottom copper and top silk screen layers to a PDF file.
  3. Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
  4. Use a Gerber viewer to double-check the output against the original PCB design.
  5. Make adjustments as needed.
  6. Submit the files to a PCB manufacturer.

Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).

See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.


#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;

use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)

#configurable settings:
#change values here instead of in main pfg2gerb.pl file

use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call

#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software.  \nGerber files MAY CONTAIN ERRORS.  Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG

use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC

use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)

#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1); 

#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
#round or square pads (> 0) and drills (< 0):
    .010, -.001,  #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
    .031, -.014,  #used for vias
    .041, -.020,  #smallest non-filled plated hole
    .051, -.025,
    .056, -.029,  #useful for IC pins
    .070, -.033,
    .075, -.040,  #heavier leads
#    .090, -.043,  #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
    .100, -.046,
    .115, -.052,
    .130, -.061,
    .140, -.067,
    .150, -.079,
    .175, -.088,
    .190, -.093,
    .200, -.100,
    .220, -.110,
    .160, -.125,  #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
    .090, -.040,  #want a .090 pad option, but use dummy hole size
    .065, -.040, #.065 x .065 rect pad
    .035, -.040, #.035 x .065 rect pad
    .001,  #too thin for real traces; use only for board outlines
    .006,  #minimum real trace width; mainly used for text
    .008,  #mainly used for mid-sized text, not traces
    .010,  #minimum recommended trace width for low-current signals
    .015,  #moderate low-voltage current
    .020,  #heavier trace for power, ground (even if a lighter one is adequate)
    .030,  #heavy-current traces; be careful with these ones!
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);

#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size:   parsed PDF diameter:      error:
#  .014                .016                +.002
#  .020                .02267              +.00267
#  .025                .026                +.001
#  .029                .03167              +.00267
#  .033                .036                +.003
#  .040                .04267              +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
    HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
    RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
    SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
    RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
    TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
    REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects

#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
    CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
    CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
    SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
    WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
    RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found

#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches

#line join/cap styles:
use constant
    CAP_NONE => 0, #butt (none); line is exact length
    CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
    CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
    CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
#number of elements in each shape type:
use constant
    RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
    LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
    CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
    CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
    rect => RECT_SHAPELEN,
    line => LINE_SHAPELEN,
    curve => CURVE_SHAPELEN,
    circle => CIRCLE_SHAPELEN,

#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions

# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?

#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes. 
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes

#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches

# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)

# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time

# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const

use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool

my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time

print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load


#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html

#my $caller = "pdf2gerb::";

#sub cfg
#    my $proto = shift;
#    my $class = ref($proto) || $proto;
#    my $settings =
#    {
#        $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
#    };
#    bless($settings, $class);
#    return $settings;

#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;

#print STDERR "read cfg file\n";

#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names

#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }

Download Details:

Author: swannman
Source Code: https://github.com/swannman/pdf2gerb

License: GPL-3.0 license


What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

Gordon  Matlala

Gordon Matlala


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!


  • Ruby >= 2.3.0


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'

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.

  - 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.


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
  # default enabled processors
    - table-processor
    - mathjax-processor
    - plantuml-processor
    - mermaid-processor
    - polyfill-processor
    - media-processor
    - emoji-processor
    - element-processor
      - https://polyfill.io/v3/polyfill.min.js?features=es6
      - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
          - ['$','$']
          - ['\(','\)']
          - ['$$','$$']
          - ['\[','\]']
        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)
    mode: default  # mode value 'pre-fetch' for fetching image at building stage
      class: plantuml
      code: 'plantuml!'
      custom: ['@startuml', '@enduml']
    src: http://www.plantuml.com/plantuml/svg/
    mode: default  # mode value 'pre-fetch' for fetching image at building stage
      class: mermaid
      code: 'mermaid!'
      custom: ['@startmermaid', '@endmermaid']
      theme: default
    src: https://mermaid.ink/svg/
      id: 'media-{id}'
      class: 'media'
      width: '100%'
      height: 350
      frameborder: 0
      style: 'max-width: 600px; outline: none;'
      allow: 'encrypted-media; picture-in-picture'
      class: emoji
    src: https://github.githubassets.com/images/icons/emoji/


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
Pyruvaye oxidation2 NADH5 ATP
Citric acid cycle2 ATP
30–32 ATP


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


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
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
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:


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:

Bob -> Alice : hello world


Bob -> Alice : hello

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:

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


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

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:





[{reference}]: {media-link}

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



Youtube Usage



Vimeo Usage



DailyMotion Usage



Spotify Usage


Spotify Podcast Usage


SoundCloud Usage


General Video Usage




General Audio Usage



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

Bob -> Alice : hello

## Video Usage


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.


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


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

Code above would be parsed as:


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


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:

    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
      - 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)
                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.

      - a:                                     # Replace all `a` tags
            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.

      - 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.

      - 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.


  • 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.


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 

Mathew Rini


How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

  • React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
  • React.js and React Native have similar syntax and workflows, but their implementation is quite different.
  • React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
  • React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

  • United States- $120,000
  • Canada - $110,000
  • United Kingdom - $71,820
  • The Netherlands $49,095
  • Spain - $35,423.00
  • France - $44,284
  • Ukraine - $28,990
  • India - $9,843
  • Sweden - $55,173
  • Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

  • Conduct thorough candidate research, including portfolios and areas of expertise.
  • Before you sit down with your interviewing panel, do some homework.
  • Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer