Package Exports

doiuse

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Readme

doiuse

Lint CSS for browser support against caniuse database.

NOTE: This is a very, very initial release. Feedback or contributions are quite welcome!

TL;DR

Command Line

doiuse --browsers "ie >= 9, > 1%, last 2 versions" main.css

Sample output:

/projects/website/main.css: line 5, col 3 - CSS3 Box-sizing not supported by: IE (8,9,10,11), Chrome (36,37,38), Safari (8,7.1), Opera (24,25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10,11)
/projects/website/main.css: line 6, col 3 - CSS3 Box-sizing not supported by: IE (8,9,10,11), Chrome (36,37,38), Safari (8,7.1), Opera (24,25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10,11)
/projects/website/main.css: line 8, col 3 - CSS user-select: none not supported by: IE (8,9)
/projects/website/main.css: line 9, col 3 - CSS user-select: none not supported by: IE (8,9)
/projects/website/main.css: line 10, col 3 - CSS user-select: none not supported by: IE (8,9)
/projects/website/main.css: line 11, col 3 - CSS user-select: none not supported by: IE (8,9)
/projects/website/main.css: line 12, col 3 - CSS user-select: none not supported by: IE (8,9)
/projects/website/main.css: line 13, col 3 - Pointer events not supported by: IE (8,9,10), Firefox (32,33), Chrome (36,37,38), Safari (8,7.1), Opera (24,25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10)
/projects/website/main.css: line 14, col 3 - Pointer events not supported by: IE (8,9,10), Firefox (32,33), Chrome (36,37,38), Safari (8,7.1), Opera (24,25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10)
/projects/website/main.css: line 32, col 3 - CSS3 Transforms not supported by: IE (8)

JS

var postcss = require('postcss');
var doiuse = require('doiuse');

postcss(doiuse({
  browsers:['ie >= 6', '> 1%'],
  onUnsupportedFeatureUse: function(usageInfo) {
    console.log(usageInfo.message);
  }
})).process("a { background-size: cover; }")

How it works

In particular, the approach to detecting features usage is currently quite naive.

Refer to the data in /src/data/features.coffee.

If a feature in that dataset only specifies properties, we just use those properties for regex/substring matches against the properties used in the input CSS.
If a feature also specifies values, then we also require that the associated value matches one of those values.

TODO:

Support @-rules
Allow each feature to have multiple instances of the match criteria laid out above, so that different, disjoint (property, value) combinations can be used to detect a feature.
Subfeatures, in to allow a slightly looser coupling with caniuse-db's structure (for handling, e.g., partial support, the different flexbox versions, etc.)
Prefix-aware testing: i.e., pass along a list of prefixes used with a given feature. (This is low priority: just use autoprefixer.)

API Details:

postcss(doiuse(opts)).process(css), where opts is:

{
  browserSelection: ['ie >= 8', '> 1%'] // an autoprefixer-like array of browsers.
  onUnsupportedFeatureUse: function(usageInfo) { } // a callback for usages of features not supported by the selected browsers
}

And usageInfo looks like this:

{
  message: '<input source>: line <l>, col <c> - CSS3 Gradients not supported by: IE (8)'
  feature: 'css-gradients', //slug identifying a caniuse-db feature
  featureData:{
    title: 'CSS Gradients',
    missing: "IE (8)" // string of browsers missing support for this feature.
    missingData: {
      // map of browser -> version -> (lack of)support code
      ie: { '8': 'n' }
    },
    caniuseData: { // data from caniuse-db/features-json/[feature].json }
  },
  usage: {} //the postcss node where that feature is being used.
}

Called once for each usage of each css feature not supported by the selected
browsers.

License

MIT