gulp-changed

Only pass through changed files

No more wasting precious time on processing unchanged files.

By default it's only able to detect whether files in the stream changed. If you require something more advanced like knowing if imports/dependencies changed, create a custom comparator, or use another plugin.

Install

1npm install --save-dev gulp-changed

Usage

1import gulp from 'gulp';
2import changed from 'gulp-changed';
3import ngAnnotate from 'gulp-ng-annotate'; // Just as an example
4
5const SOURCE = 'src/*.js';
6const DESTINATION = 'dist';
7
8exports.default = () => (
9	gulp.src(SOURCE)
10		.pipe(changed(DESTINATION))
11		// `ngAnnotate` will only get the files that
12		// changed since the last time it was run
13		.pipe(ngAnnotate())
14		.pipe(gulp.dest(DESTINATION))
15);

API

changed(destination, options?)

destination

Type: string | Function

Destination directory. Same as you put into gulp.dest().

This is needed to be able to compare the current files with the destination files.

Can also be a function returning a destination directory path.

options

Type: object

cwd

Type: string
Default: process.cwd()

Working directory the folder is relative to.

extension

Type: string

Extension of the destination files.

Useful if it differs from the original, like in the example below:

1export const jade = () => (
2	gulp.src('src/**/*.jade')
3		.pipe(changed('app', {extension: '.html'}))
4		.pipe(jade())
5		.pipe(gulp.dest('app'))
6);

hasChanged

Type: Function
Default: compareLastModifiedTime

Function that determines whether the source file is different from the destination file.

Built-in comparators

Named imports:

• compareLastModifiedTime
• compareContents

Example

1import {compareContents} from 'gulp-changed';
2
3export const jade = () => (
4	gulp.src('src/**/*.jade')
5		.pipe(changed('app', {hasChanged: compareContents}))
6		.pipe(jade())
7		.pipe(gulp.dest('app'))
8);

You can also specify a custom comparator function, which will receive the following arguments:

• sourceFile (Vinyl file object)
• destinationPath (string) - The destination for sourceFile as an absolute path

The function is expected to return sourceFile | Promise<sourceFile> if it passes some comparison or undefined | Promise<undefined>. Examples.

transformPath

Type: Function

Function to transform the path to the destination file. Should return the absolute path to the (renamed) destination file.

Useful if you rename your file later on, like in the below example:

1export const marked = () => (
2	gulp.src('src/content/about.md')
3		.pipe(changed('dist', {
4			transformPath: newPath => path.join(path.dirname(newPath), path.basename(newPath, '.md'), 'index.html')
5		}))
6		.pipe(marked())
7		.pipe(rename(newPath => path.join(path.dirname(newPath), path.basename(newPath, '.md'), 'index.html')))
8		.pipe(gulp.dest('dist'))
9);

In-place change monitoring

If you're looking to process source files in-place without any build output (formatting, linting, etc), have a look at gulp-changed-in-place.