gulp-postcss

What is gulp-postcss?

gulp-postcss is a Gulp plugin to pipe CSS through several PostCSS plugins, allowing you to transform styles with JS plugins. It is highly flexible and can be used for a variety of CSS processing tasks such as autoprefixing, minification, and linting.

What are gulp-postcss's main functionalities?

Autoprefixing

This feature allows you to automatically add vendor prefixes to your CSS rules using the autoprefixer PostCSS plugin. This ensures compatibility with different browsers.

const gulp = require('gulp');
const postcss = require('gulp-postcss');
const autoprefixer = require('autoprefixer');

gulp.task('css', function () {
  return gulp.src('src/*.css')
    .pipe(postcss([autoprefixer()]))
    .pipe(gulp.dest('dest'));
});

CSS Minification

This feature allows you to minify your CSS files using the cssnano PostCSS plugin, which helps in reducing the file size and improving load times.

const gulp = require('gulp');
const postcss = require('gulp-postcss');
const cssnano = require('cssnano');

gulp.task('minify-css', function () {
  return gulp.src('src/*.css')
    .pipe(postcss([cssnano()]))
    .pipe(gulp.dest('dest'));
});

Linting CSS

This feature allows you to lint your CSS files using the stylelint PostCSS plugin, which helps in maintaining code quality and consistency.

const gulp = require('gulp');
const postcss = require('gulp-postcss');
const stylelint = require('stylelint');
const reporter = require('postcss-reporter');

gulp.task('lint-css', function () {
  return gulp.src('src/*.css')
    .pipe(postcss([
      stylelint(),
      reporter({ clearReportedMessages: true })
    ]));
});

Other packages similar to gulp-postcss

gulp-sass

gulp-sass is a Gulp plugin for compiling Sass to CSS. While gulp-postcss focuses on transforming CSS with various plugins, gulp-sass is specifically designed for compiling Sass files. It is often used in conjunction with gulp-postcss for a complete CSS processing workflow.

gulp-less

gulp-less is a Gulp plugin for compiling Less to CSS. Similar to gulp-sass, it is focused on compiling Less files rather than transforming CSS with plugins. It can be used alongside gulp-postcss for additional CSS transformations.

gulp-clean-css

gulp-clean-css is a Gulp plugin for minifying CSS files. While gulp-postcss can achieve minification through plugins like cssnano, gulp-clean-css is a dedicated tool for this purpose and may offer more specialized options for minification.

README

gulp-postcss

PostCSS gulp plugin to pipe CSS through several plugins, but parse CSS only once.

Install

$ npm install --save-dev gulp-postcss

Install required postcss plugins separately. E.g. for autoprefixer, you need to install autoprefixer package.

Basic usage

The configuration is loaded automatically from postcss.config.js as described here, so you don't have to specify any options.

var postcss = require('gulp-postcss');
var gulp = require('gulp');

gulp.task('css', function () {
    return gulp.src('./src/*.css')
        .pipe(postcss())
        .pipe(gulp.dest('./dest'));
});

Passing plugins directly

var postcss = require('gulp-postcss');
var gulp = require('gulp');
var autoprefixer = require('autoprefixer');
var cssnano = require('cssnano');

gulp.task('css', function () {
    var plugins = [
        autoprefixer({browsers: ['last 1 version']}),
        cssnano()
    ];
    return gulp.src('./src/*.css')
        .pipe(postcss(plugins))
        .pipe(gulp.dest('./dest'));
});

Passing additional options to PostCSS

The second optional argument to gulp-postcss is passed to PostCSS.

This, for instance, may be used to enable custom parser:

var gulp = require('gulp');
var postcss = require('gulp-postcss');
var nested = require('postcss-nested');
var sugarss = require('sugarss');

gulp.task('default', function () {
    var plugins = [nested];
    return gulp.src('in.sss')
        .pipe(postcss(plugins, { parser: sugarss }))
        .pipe(gulp.dest('out'));
});

Using a custom processor

var postcss = require('gulp-postcss');
var cssnext = require('postcss-cssnext');
var opacity = function (css, opts) {
    css.eachDecl(function(decl) {
        if (decl.prop === 'opacity') {
            decl.parent.insertAfter(decl, {
                prop: '-ms-filter',
                value: '"progid:DXImageTransform.Microsoft.Alpha(Opacity=' + (parseFloat(decl.value) * 100) + ')"'
            });
        }
    });
};

gulp.task('css', function () {
    var plugins = [
        cssnext({browsers: ['last 1 version']}),
        opacity
    ];
    return gulp.src('./src/*.css')
        .pipe(postcss(plugins))
        .pipe(gulp.dest('./dest'));
});

Source map support

Source map is disabled by default, to extract map use together with gulp-sourcemaps.

return gulp.src('./src/*.css')
    .pipe(sourcemaps.init())
    .pipe(postcss(plugins))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('./dest'));

Advanced usage

If you want to configure postcss on per-file-basis, you can pass a callback that receives vinyl file object and returns { plugins: plugins, options: options }. For example, when you need to parse different extensions differntly:

var gulp = require('gulp');
var postcss = require('gulp-postcss');

gulp.task('css', function () {
    function callback(file) {
        return {
            plugins: [
                require('postcss-import')({ root: file.dirname }),
                require('postcss-modules')
            ],
            options: {
                parser: file.extname === '.sss' ? require('sugarss') : false
            }
        }
    }
    return gulp.src('./src/*.css')
        .pipe(postcss(callback))
        .pipe(gulp.dest('./dest'));
});

The same result may be achieved with postcss-load-config, because it receives ctx with the context options and the vinyl file.

var gulp = require('gulp');
var postcss = require('gulp-postcss');

gulp.task('css', function () {
    var contextOptions = { modules: true };
    return gulp.src('./src/*.css')
        .pipe(postcss(contextOptions))
        .pipe(gulp.dest('./dest'));
});

module.exports = function (ctx) {
    var file = ctx.file;
    var options = ctx.options;
    return {
        parser: file.extname === '.sss' ? : 'sugarss' : false,
        plugins: {
           'postcss-import': { root: file.dirname }
           'postcss-modules': options.modules ? {} : false
        }
    }
})

Changelog

• 7.0.0

  • Bump PostCSS to 6.0
  • Smaller module size
  • Use eslint instead of jshint

• 6.4.0

  • Add more details to PluginError object

• 6.3.0

  • Integrated with postcss-load-config
  • Added a callback to configure postcss on per-file-basis
  • Dropped node 0.10 support

• 6.2.0

  • Fix syntax error message for PostCSS 5.2 compatibility

• 6.1.1

  • Fixed the error output

• 6.1.0

  • Support for null files
  • Updated dependencies

• 6.0.1

  • Added an example and a test to pass options to PostCSS (e.g. syntax option)
  • Updated vinyl-sourcemaps-apply to 0.2.0

• 6.0.0

  • Updated PostCSS to version 5.0.0

• 5.1.10

  • Use autoprefixer in README

• 5.1.9

  • Prevent unhandled exception of the following pipes from being suppressed by Promise

• 5.1.8

  • Prevent stream’s unhandled exception from being suppressed by Promise

• 5.1.7

  • Updated direct dependencies

• 5.1.6

  • Updated CssSyntaxError check

• 5.1.4

  • Simplified error handling
  • Simplified postcss execution with object plugins

• 5.1.3 Updated travis banner

• 5.1.2 Transferred repo into postcss org on github

• 5.1.1

  • Allow override of to option

• 5.1.0 PostCSS Runner Guidelines

  • Set from and to processing options
  • Don't output js stack trace for CssSyntaxError
  • Display result.warnings() content

• 5.0.1

  • Fix to support object plugins

• 5.0.0

  • Use async API

• 4.0.3

  • Fixed bug with relative source map

• 4.0.2

  • Made PostCSS a simple dependency, because peer dependency is deprecated

• 4.0.1

  • Made PostCSS 4.x a peer dependency

• 4.0.0

  • Updated PostCSS to 4.0

• 3.0.0

  • Updated PostCSS to 3.0 and fixed tests

• 2.0.1

  • Added Changelog
  • Added example for a custom processor in README

• 2.0.0

  • Disable source map by default
  • Test source map
  • Added Travis support
  • Use autoprefixer-core in README

• 1.0.2

  • Improved README

• 1.0.1

  • Don't add source map comment if used with gulp-sourcemaps

• 1.0.0

  • Initial release