isabella232 / postcss-plugin-context

Limit a PostCSS processor to a local stylesheet context.

postcss-plugin-context

Limit a PostCSS processor to a local stylesheet context.

Install

With npm do:

npm install postcss-plugin-context --save

Example

This plugin is useful should you need to contextualize another processor inside your CSS file. For example, postcss-map will allow you to specify a short syntax if only one file is specified. Using this module, we can limit the scope of the transform to be of our choice, rather than the module's. In this example, only the first ruleset is actually passed to postcss-map, and the rest of the CSS file is untouched.

Simply define a @context block inside your CSS file, such as:

@context brandColors {
    h1 {
        color: map(primary);
    }
}

Then, the plugin will work on the brandColors context. The @context block is removed automatically for you after the fact.

var postcss = require('postcss');
var map = require('postcss-map');
var context = require('postcss-plugin-context');

var css = '@context brandColors { h1 { color: map(primary) } } h2 { color: map(primary) }';
console.log(postcss([
    context({
        brandColors: map({
            maps: ['brand.yml']
        })
    })
]).process(css).css);

// => 'h1 { color: red } h2 { color: map(primary) }'

Note that you can pass multiple processors to a single context block:

h1 {
    @context brandColors, size {
        color: map(primary);
        size: 100px;
    }
}

Outputs:

h1 {
    color: red;
    width: 100px;
    height: 100px;
}

Note that a context may also be defined across a whole file; if you specify @context without curly braces. For example:

@context size;

h1 {
    size: 100px;
}

Outputs:

h1 {
    width: 100px;
    height: 100px;
}

API

context(plugins)

plugins

Type: object Required value.

Pass an object of processors to contextualize.

context({
    brandColors: map({maps: ['brand.yml']})
    size: require('postcss-size')
});

Contributing

Pull requests are welcome. If you add functionality, then please add unit tests to cover it.

License

MIT © Ben Briggs