postcss-filter-plugins

Exclude/warn on duplicated PostCSS plugins.

With npm do:

npm install postcss-filter-plugins --save

Note that this plugin does not actually transform your CSS; instead, it ensures that plugins in the PostCSS instance are not duplicated. It is intended to be used by plugin packs such as cssnano or cssnext.

var counter = postcss.plugin('counter', function () {
    return function (css) {
        css.eachDecl('foo', function (decl) {
            let value = parseInt(decl.value, 10);
            value += 1;
            decl.value = String(value);
        });
    }
});

var css = 'h1 { foo: 1 }';
var out = postcss([ filter(), counter(), counter() ]).process(css).css;

console.log(out);
// => h1 { foo: 2 }

Type: string Default: both

Pass forward, backward, or both to customise the direction in which the plugin will look in the plugins array. See the tests for examples on how this works.

postcss([ filter({
    direction: 'forward'
}) ]).process(css).css);

Type: array Default: [] (empty)

Plugins that should be excluded from the filter. Pass an array of plugin names.

postcss([ filter({
    exclude: ['autoprefixer']
}) ]).process(css).css);

Type: boolean Default: false

Set this to true to disable the plugin from emitting any PostCSS warnings.

postcss([ filter({
    silent: true
}) ]).process(css).css);

Type: function Default: format function

This function will be passed each PostCSS plugin object. You are expected to return a string from each call, which is then used to warn the user about her duplicated plugins.

postcss([ filter({
    template: function (plugin) {
        return 'Duplicate plugin found: ' + plugin.postcssPlugin;
    }
}) ]).process(css).css);

See the PostCSS documentation for examples for your environment.

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

MIT © Ben Briggs