The streaming build system

What is gulp?

• Automation - gulp is a toolkit that helps you automate painful or time-consuming tasks in your development workflow.
• Platform-agnostic - Integrations are built into all major IDEs and people are using gulp with PHP, .NET, Node.js, Java, and other platforms.
• Strong Ecosystem - Use npm modules to do anything you want + over 2000 curated plugins for streaming file transformations
• Simple - By providing only a minimal API surface, gulp is easy to learn and simple to use

Installation

There are a few ways to install:

• gulp v4.0.0 - npm install gulp@next
• gulp v4.0.0-alpha.3 - npm install gulpjs/gulp#v4.0.0-alpha.3
• gulp v3.9.1 - npm install gulp

Documentation

For a Getting started guide, API docs, recipes, making a plugin, etc. check out our docs!

• Check out the documentation for v4.0.0! Excuse our dust; these docs might be behind while we get everything updated. Please open an issue if something isn't working.
• Using the older v3.9.1? Check out the documentation at the v3.9.1 tag!

Sample gulpfile.js

This file will give you a taste of what gulp does.

var gulp = require('gulp');
var less = require('gulp-less');
var babel = require('gulp-babel');
var concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var rename = require('gulp-rename');
var cleanCSS = require('gulp-clean-css');
var del = require('del');

var paths = {
  styles: {
    src: 'src/styles/**/*.less',
    dest: 'assets/styles/'
  },
  scripts: {
    src: 'src/scripts/**/*.js',
    dest: 'assets/scripts/'
  }
};

/* Not all tasks need to use streams, a gulpfile is just another node program
 * and you can use all packages available on npm, but it must return either a
 * Promise, a Stream or take a callback and call it
 */
function clean() {
  // You can use multiple globbing patterns as you would with `gulp.src`,
  // for example if you are using del 2.0 or above, return its promise
  return del([ 'assets' ]);
}

/*
 * Define our tasks using plain functions
 */
function styles() {
  return gulp.src(paths.styles.src)
    .pipe(less())
    .pipe(cleanCSS())
    // pass in options to the stream
    .pipe(rename({
      basename: 'main',
      suffix: '.min'
    }))
    .pipe(gulp.dest(paths.styles.dest));
}

function scripts() {
  return gulp.src(paths.scripts.src, { sourcemaps: true })
    .pipe(babel())
    .pipe(uglify())
    .pipe(concat('main.min.js'))
    .pipe(gulp.dest(paths.scripts.dest));
}

function watch() {
  gulp.watch(paths.scripts.src, scripts);
  gulp.watch(paths.styles.src, styles);
}

/*
 * You can use CommonJS `exports` module notation to declare tasks
 */
exports.clean = clean;
exports.styles = styles;
exports.scripts = scripts;
exports.watch = watch;

/*
 * Specify if tasks run in series or parallel using `gulp.series` and `gulp.parallel`
 */
var build = gulp.series(clean, gulp.parallel(styles, scripts));

/*
 * You can still use `gulp.task` to expose tasks
 */
gulp.task('build', build);

/*
 * Define default task that can be called by just running `gulp` from cli
 */
gulp.task('default', build);

Use latest JavaScript version in your gulpfile

Node already supports a lot of ES2015, to avoid compatibility problem we suggest to install Babel and rename your gulpfile.js as gulpfile.babel.js.

npm install --save-dev babel-register babel-preset-es2015

Then create a .babelrc file with the preset configuration.

{
  "presets": [ "es2015" ]
}

And here's the same sample from above written in ES2015.

import gulp from 'gulp';
import less from 'gulp-less';
import babel from 'gulp-babel';
import concat from 'gulp-concat';
import uglify from 'gulp-uglify';
import rename from 'gulp-rename';
import cleanCSS from 'gulp-clean-css';
import del from 'del';

const paths = {
  styles: {
    src: 'src/styles/**/*.less',
    dest: 'assets/styles/'
  },
  scripts: {
    src: 'src/scripts/**/*.js',
    dest: 'assets/scripts/'
  }
};

/*
 * For small tasks you can export arrow functions
 */
export const clean = () => del([ 'assets' ]);

/*
 * You can also declare named functions and export them as tasks
 */
export function styles() {
  return gulp.src(paths.styles.src)
    .pipe(less())
    .pipe(cleanCSS())
    // pass in options to the stream
    .pipe(rename({
      basename: 'main',
      suffix: '.min'
    }))
    .pipe(gulp.dest(paths.styles.dest));
}

export function scripts() {
  return gulp.src(paths.scripts.src, { sourcemaps: true })
    .pipe(babel())
    .pipe(uglify())
    .pipe(concat('main.min.js'))
    .pipe(gulp.dest(paths.scripts.dest));
}

 /*
  * You could even use `export as` to rename exported tasks
  */
function watchFiles() {
  gulp.watch(paths.scripts.src, scripts);
  gulp.watch(paths.styles.src, styles);
}
export { watchFiles as watch };

/*
 * You can still use `gulp.task`
 * for example to set task names that would otherwise be invalid
 */
const build = gulp.series(clean, gulp.parallel(styles, scripts));
gulp.task('build', build);

/*
 * Export a default task
 */
export default build;

Incremental Builds

You can filter out unchanged files between runs of a task using the gulp.src function's since option and gulp.lastRun:

const paths = {
  ...
  images: {
    src: 'src/images/**/*.{jpg,jpeg,png}',
    dest: 'build/img/'
  }
}

function images() {
  return gulp.src(paths.images.src, {since: gulp.lastRun(images)})
    .pipe(imagemin({optimizationLevel: 5}))
    .pipe(gulp.dest(paths.images.dest));
}

function watch() {
  gulp.watch(paths.images.src, images);
}

Task run times are saved in memory and are lost when gulp exits. It will only save time during the watch task when running the images task for a second time.

If you want to compare modification time between files instead, we recommend these plugins:

• gulp-changed;
• or gulp-newer - supports many:1 source:dest.

gulp-newer example:

function images() {
  var dest = 'build/img';
  return gulp.src(paths.images)
    .pipe(newer(dest))  // pass through newer images only
    .pipe(imagemin({optimizationLevel: 5}))
    .pipe(gulp.dest(dest));
}

If you can't simply filter out unchanged files, but need them in a later phase of the stream, we recommend these plugins:

• gulp-cached - in-memory file cache, not for operation on sets of files
• gulp-remember - pairs nicely with gulp-cached

gulp-remember example:

function scripts() {
  return gulp.src(scriptsGlob)
    .pipe(cache('scripts'))    // only pass through changed files
    .pipe(header('(function () {')) // do special things to the changed files...
    .pipe(footer('})();'))     // for example,
                               // add a simple module wrap to each file
    .pipe(remember('scripts')) // add back all files to the stream
    .pipe(concat('app.js'))    // do things that require all files
    .pipe(gulp.dest('public/'))
}

Want to contribute?

Anyone can help make this project better - check out our Contributing guide!

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