PostCSS-RTL

PostCSS-plugin for RTL-adaptivity

Generates RTL rules with flipped properties.
Use one file for both directions!

• Examples
  • Simple properties
  • Animations
  • Value directives
  • Property directives
  • Ignoring specific declarations
• Usage
  • With Webpack
  • With Gulp
  • Options
• Thanks

Examples

Simple properties

In most cases all you need is flip property name or value
from left to right or change values order in full-valued shorthand
from top-right-bottom-left to top-left-bottom-right.

LTR input:

 .foo {
    float: right;
    margin-left: 13px;
    text-align: right;
    font-size: 13px;
    border-color: lightgray;
    border-width: 2px 0 2px 2px;
    border-style: solid dashed solid solid
}

.foo {
    text-align: center;
}

LTR+RTL output:

 .foo {
    font-size: 13px
}

[dir] .foo {
    border-color: lightgray
}

[dir="ltr"] .foo {
    float: right;
    margin-left: 13px;
    text-align: right;
    border-width: 2px 0 2px 2px;
    border-style: solid dashed solid solid
}

[dir="rtl"] .foo {
    float: left;
    margin-right: 13px;
    text-align: left;
    border-width: 2px 2px 2px 0;
    border-style: solid solid solid dashed
}

[dir] .foo {
    text-align: center
}

Animations

Flippable keyframes-animations will be splitted to two
direction-based rules with -ltr or -rtl suffixes

LTR input:

 .foo {
    animation: 1s slide 0s ease-in-out
}

@keyframes slide {
    from {
        transform: translate( -1000px )
    }
    to {
        transform: translate( 0 )
    }
}

LTR+RTL output:

 [dir="ltr"] .foo {
    animation: 1s slide-ltr 0s ease-in-out
}

[dir="rtl"] .foo {
    animation: 1s slide-rtl 0s ease-in-out
}

@keyframes slide-ltr {
    from {
        transform: translate( -1000px )
    }
    to {
        transform: translate( 0 )
    }
}

@keyframes slide-rtl {
    from {
        transform: translate( 1000px )
    }
    to {
        transform: translate( 0 )
    }
}

Value directives

To transform declaration values use value directives:

• /* rtl:prepend:{value} */ - to prepend the {value} before the current value
• /* rtl:append:{value} */ - to append the {value} after the current value
• /* rtl:{value} */ - to replace the current value with the supplied value

Source

 .foo {
    font-weight: bold;
    font-family: "Droid Sans", "Helvetica Neue", Arial, sans-serif/*rtl:prepend:"Droid Arabic Kufi",*/;
    transform: rotate(45deg)/* rtl:append: scaleX(-1) */;
    flex-direction: row/* rtl: row-reverse */;
}

Result

 .foo {
    font-weight: bold;
}

[dir=ltr] .foo {
    font-family: "Droid Sans", "Helvetica Neue", Arial, sans-serif/*rtl:prepend:"Droid Arabic Kufi",*/;
    transform: rotate(45deg)/* rtl:append: scaleX(-1) */;
    flex-direction: row/* rtl: row-reverse */;
}

[dir=rtl] .foo {
    font-family: "Droid Arabic Kufi", "Droid Sans", "Helvetica Neue", Arial, sans-serif;
    transform: rotate(45deg) scaleX(-1);
    flex-direction: row-reverse;
}

Property directives

To transform declaration property name use property directives:

• /* rtl:as:{prop} */ - to process the property as {prop}. Usable for custom properties (uses rtlcss aliases under the hood)

Source

 :root {
    --padding /* rtl:as:padding */: 1rem 2rem 3rem 4rem;
}

Result

 [dir=ltr]:root {
    --padding /* rtl:as:padding */: 1rem 2rem 3rem 4rem;
}

[dir=rtl]:root {
    --padding /* rtl:as:padding */: 1rem 4rem 3rem 2rem;
}

Ignoring specific declarations

To skip flipping specific declarations use some of supported directives:

• /* rtl:ignore */ - to ignore the following rule or the containing declaration
• /* rtl:begin:ignore */ and /* rtl:end:ignore */ - to ignore rules within scope

Ignore one rule:

 /* rtl:ignore */
.foo {
    padding-left: 0
}

Block-syntax to ignore rules within scope:

 /* rtl:begin:ignore */
.foo {
    padding-left: 0
}
.bar {
    direction: ltr
}
/* rtl:end:ignore */

Value-syntax to ignore a single CSS declaration:

 .foo {
    margin-left: 20px;
    padding-right: 20px /* rtl:ignore */;
}

/*! notation will work too:

 /*! rtl:ignore */
.foo {
    padding-left: 0
}

Usage

1. Plug it to PostCSS

    const postcss = require('postcss')
   const rtl = require('postcss-rtl')
   
   postcss([ rtl( options ) ])
   

   See PostCSS docs for examples for your environment.

2. Manage direction by switching between dir="ltr" and dir="rtl" on <html> element.

With Webpack:

 module.exports = {
  module: {
    rules: [ {
      test: /\.css$/,
      use: [
        { loader: 'style-loader' },
        { loader: 'css-loader' },
        { loader: 'postcss-loader',
          options: {
            plugins: function () {
              return [ require( 'postcss-rtl' )( options ) ]
            }
          }
        }
      ]
    } ]
  }
}

With Gulp:

 gulp.src( 'style.css' )
    .pipe( postcss( [ rtl( options ) ]) )
    .pipe( gulp.dest( './dest' ) )

Options

• addPrefixToSelector: Custom function for adding prefix to selector. Optional.
  Example:

   function addPrefixToSelector ( selector, prefix ) {
      return `${prefix} > ${selector}` // Make selectors like [dir=rtl] > .selector
  }
  

  note: the returned string must include prefix to avoid an infinite recursion

• onlyDirection: generate only one-direction version: ltr or rtl

• prefixType: Switches between adding attributes and classes. Optional:

  • attribute (by default, recommended): .foo => [dir=rtl] .foo
  • class (useful for IE6): .foo => .dir-rtl .foo

• prefix: Uses a custom string, instead of 'dir', for the added attribute and class selectors

  • e.g. 'data-my-custom-dir' (for attribute prefixType): .foo => [data-my-custom-dir=rtl] .foo
  • e.g. 'my-custom-dir' (for class prefixType): .foo => .my-custom-dir-rtl .foo

• removeComments (default: true): remove rtl:* comments after process them

• fromRTL (default: false): assume all styles are written in RTL direction and generate corresponding LTR styles for them

• blacklist: the array of css properties which processing will be ignored
  Example:

   ['padding-left', 'padding-right']
  

• whitelist: the array of css properties which (and only them) will be processed
  Example:

   ['margin', 'border-color']
  

• aliases: check rtlcss aliases documentation
  Example:

   {
      `--spacing`: 'padding'
  }
  

Thanks

Great thanks to projects:

• PostCSS
• RTLCSS