gulp API docs

gulp.src(globs[, options])

Emits files matching provided glob or an array of globs. Returns a stream of Vinyl files that can be piped to plugins.

gulp.src('client/templates/*.jade')
  .pipe(jade())
  .pipe(minify())
  .pipe(gulp.dest('build/minified_templates'));

globs

Type: String or Array

Glob or array of globs to read. Globs use node-glob syntax except that negation is fully supported.

A glob that begins with ! excludes matching files from the glob results up to that point. For example, consider this directory structure:

client/
  a.js
  bob.js
  bad.js

The following expression matches a.js and bad.js:

gulp.src(['client/*.js', '!client/b*.js', 'client/bad.js'])

options

Type: Object

Options to pass to node-glob through glob-stream.

gulp supports all options supported by node-glob and glob-stream except ignore and adds the following options.

options.buffer

Type: Boolean Default: true

Setting this to false will return file.contents as a stream and not buffer files. This is useful when working with large files. Note: Plugins might not implement support for streams.

options.read

Type: Boolean Default: true

Setting this to false will return file.contents as null and not read the file at all.

options.base

Type: String Default: everything before a glob starts (see glob2base)

E.g., consider somefile.js in client/js/somedir:

gulp.src('client/js/**/*.js') // Matches 'client/js/somedir/somefile.js' and resolves `base` to `client/js/`
  .pipe(minify())
  .pipe(gulp.dest('build'));  // Writes 'build/somedir/somefile.js'

gulp.src('client/js/**/*.js', { base: 'client' })
  .pipe(minify())
  .pipe(gulp.dest('build'));  // Writes 'build/js/somedir/somefile.js'

gulp.dest(path[, options])

Can be piped to and it will write files. Re-emits all data passed to it so you can pipe to multiple folders. Folders that don't exist will be created.

gulp.src('./client/templates/*.jade')
  .pipe(jade())
  .pipe(gulp.dest('./build/templates'))
  .pipe(minify())
  .pipe(gulp.dest('./build/minified_templates'));

The write path is calculated by appending the file relative path to the given destination directory. In turn, relative paths are calculated against the file base. See gulp.src above for more info.

path

Type: String or Function

The path (output folder) to write files to. Or a function that returns it, the function will be provided a vinyl File instance.

options

Type: Object

options.cwd

Type: String Default: process.cwd()

cwd for the output folder, only has an effect if provided output folder is relative.

options.mode

Type: String Default: 0777

Octal permission string specifying mode for any folders that need to be created for output folder.

gulp.task(name [, deps, fn])

Define a task using Orchestrator.

gulp.task('somename', function() {
  // Do stuff
});

name

Type: String

The name of the task. Tasks that you want to run from the command line should not have spaces in them.

deps

Type: Array

An array of tasks to be executed and completed before your task will run.

gulp.task('mytask', ['array', 'of', 'task', 'names'], function() {
  // Do stuff
});

Note: Are your tasks running before the dependencies are complete? Make sure your dependency tasks are correctly using the async run hints: take in a callback or return a promise or event stream.

You can also omit the function if you only want to run a bundle of dependency tasks:

gulp.task('build', ['array', 'of', 'task', 'names']);

Note: The tasks will run in parallel (all at once), so don't assume that the tasks will start/finish in order.

fn

Type: Function

The function performs the task's main operations. Generally this takes the form of:

gulp.task('buildStuff', function() {
  // Do something that "builds stuff"
  var stream = gulp.src(/*some source path*/)
  .pipe(somePlugin())
  .pipe(someOtherPlugin())
  .pipe(gulp.dest(/*some destination*/));

  return stream;
  });

Async task support

Tasks can be made asynchronous if its fn does one of the following:

Accept a callback
// run a command in a shell
var exec = require('child_process').exec;
gulp.task('jekyll', function(cb) {
  // build Jekyll
  exec('jekyll build', function(err) {
    if (err) return cb(err); // return error
    cb(); // finished task
  });
});
Return a stream
gulp.task('somename', function() {
  var stream = gulp.src('client/**/*.js')
    .pipe(minify())
    .pipe(gulp.dest('build'));
  return stream;
});
Return a promise
var Q = require('q');

gulp.task('somename', function() {
  var deferred = Q.defer();

  // do async stuff
  setTimeout(function() {
    deferred.resolve();
  }, 1);

  return deferred.promise;
});

Note: By default, tasks run with maximum concurrency -- e.g. it launches all the tasks at once and waits for nothing. If you want to create a series where tasks run in a particular order, you need to do two things:

For these examples, let's presume you have two tasks, "one" and "two" that you specifically want to run in this order:

  1. In task "one" you add a hint to tell it when the task is done. Either take in a callback and call it when you're done or return a promise or stream that the engine should wait to resolve or end respectively.

  2. In task "two" you add a hint telling the engine that it depends on completion of the first task.

So this example would look like this:

var gulp = require('gulp');

// takes in a callback so the engine knows when it'll be done
gulp.task('one', function(cb) {
    // do stuff -- async or otherwise
    cb(err); // if err is not null and not undefined, the run will stop, and note that it failed
});

// identifies a dependent task must be complete before this one begins
gulp.task('two', ['one'], function() {
    // task 'one' is done now
});

gulp.task('default', ['one', 'two']);

gulp.watch(glob [, opts], tasks) or gulp.watch(glob [, opts, cb])

Watch files and do something when a file changes. This always returns an EventEmitter that emits change events.

gulp.watch(glob[, opts], tasks)

glob

Type: String or Array

A single glob or array of globs that indicate which files to watch for changes.

opts

Type: Object

Options, that are passed to gaze.

tasks

Type: Array

Names of task(s) to run when a file changes, added with gulp.task()

var watcher = gulp.watch('js/**/*.js', ['uglify','reload']);
watcher.on('change', function(event) {
  console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
});

gulp.watch(glob[, opts, cb])

glob

Type: String or Array

A single glob or array of globs that indicate which files to watch for changes.

opts

Type: Object

Options, that are passed to gaze.

cb(event)

Type: Function

Callback to be called on each change.

gulp.watch('js/**/*.js', function(event) {
  console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
});

The callback will be passed an object, event, that describes the change:

event.type

Type: String

The type of change that occurred, either added, changed or deleted.

event.path

Type: String

The path to the file that triggered the event.