Autoprefixer Rails
¶ ↑
<img align=“right” width=“94” height=“71” src=“postcss.github.io/autoprefixer/logo.svg” title=“Autoprefixer logo by Anton Lovchikov”>
Autoprefixer is a tool to parse CSS and add vendor prefixes to CSS rules using values from the Can I Use. This gem provides Ruby and Ruby on Rails integration with this JavaScript tool.
Usage¶ ↑
Windows users should install node.js. Autoprefixer Rails doesn’t work with old JScript in Windows.
Ruby on Rails¶ ↑
Add the autoprefixer-rails
gem to your Gemfile
:
gem "autoprefixer-rails"
Clear your cache:
rake tmp:clear
Write your CSS (Sass, Stylus, LESS) rules without vendor prefixes and
Autoprefixer will apply prefixes for you. For example in
app/assets/stylesheet/foobar.sass
:
:fullscreen a display: flex
Autoprefixer uses Can I Use database with browser statistics and properties support to add vendor prefixes automatically using the Asset Pipeline:
:-webkit-full-screen a { display: -webkit-box; display: -webkit-flex; display: flex } :-moz-full-screen a { display: flex } :-ms-fullscreen a { display: -ms-flexbox; display: flex } :fullscreen a { display: -webkit-box; display: -webkit-flex; display: -ms-flexbox; display: flex }
If you need to specify browsers for your Rails project, you can save them to
-
browserslist
and place it underapp/assets/stylesheets/
or any of its ancestor directories> 1% last 2 versions IE > 8 # comment
-
Or
config/autoprefixer.yml
flexbox: no-2009 browsers: - "> 1%" - "last 2 versions" - "IE > 8"
See Browserslist docs for
config format. But > 5% in US
query is not supported in
Rails, because of ExecJS limitations. You should migrate to webpack or Gulp
if you want it.
Note: you have to clear cache (rake tmp:clear
) for the
configuration to take effect.
You can get what properties will be changed using a Rake task:
rake autoprefixer:info
To disable Autoprefixer just remove postprocessor:
AutoprefixerRails.uninstall(Rails.application.assets)
Sprockets¶ ↑
If you use Sinatra or other non-Rails frameworks with Sprockets, just connect your Sprockets environment with Autoprefixer and write CSS in the usual way:
assets = Sprockets::Environment.new do |env| # Your assets settings end require "autoprefixer-rails" AutoprefixerRails.install(assets)
Ruby¶ ↑
If you need to call Autoprefixer from plain Ruby code, it’s very easy:
require "autoprefixer-rails" prefixed = AutoprefixerRails.process(css, from: 'main.css').css
You can specify browsers by browsers
option:
AutoprefixerRails.process(css, from: 'a.css', browsers: ['> 1%', 'ie 10']).css
Compass¶ ↑
You should consider using Gulp instead of Compass binary, because it has better Autoprefixer integration and many other awesome plugins.
But if you can’t move from Compass binary right now, there’s a hack to run
Autoprefixer after compass compile
.
Install autoprefixer-rails
gem:
gem install autoprefixer-rails
and add post-compile hook to config.rb
:
require 'autoprefixer-rails' on_stylesheet_saved do |file| css = File.read(file) map = file + '.map' if File.exists? map result = AutoprefixerRails.process(css, from: file, to: file, map: { prev: File.read(map), inline: false }) File.open(file, 'w') { |io| io << result.css } File.open(map, 'w') { |io| io << result.map } else File.open(file, 'w') { |io| io << AutoprefixerRails.process(css) } end end
Visual Cascade¶ ↑
By default, Autoprefixer will change CSS indentation to create nice visual cascade of prefixes.
a { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box }
You can disable it by cascade: false
in
config/autoprefixer.yml
or in process()
options.
Source Map¶ ↑
Autoprefixer will generate source map, if you set map
option
to true
in process
method.
You must set input and output CSS files paths (by from
and
to
options) to generate correct map.
result = AutoprefixerRails.process(css, map: true, from: 'main.css', to: 'main.out.css')
Autoprefixer can also modify previous source map (for example, from Sass
compilation). Just set original source map content (as string) to
map
option:
result = AutoprefixerRails.process(css, { map: File.read('main.sass.css.map'), from: 'main.sass.css', to: 'main.min.css') result.map #=> Source map from main.sass to main.min.css
See all options in PostCSS docs. AutoprefixerRails will convert Ruby style
to JS style, so you can use map: { sources_content: false }
instead of camelcase sourcesContent
.