gulp-uglify

What is gulp-uglify?

The gulp-uglify package is a Gulp plugin that minifies JavaScript files using UglifyJS. It helps in reducing the file size of JavaScript files by removing unnecessary characters, comments, and whitespace, making the code more efficient for production environments.

What are gulp-uglify's main functionalities?

Basic Minification

This feature allows you to minify JavaScript files. The code sample demonstrates how to create a Gulp task that takes JavaScript files from the 'src' directory, minifies them using gulp-uglify, and outputs the minified files to the 'dist' directory.

const gulp = require('gulp');
const uglify = require('gulp-uglify');

gulp.task('minify-js', function() {
  return gulp.src('src/*.js')
    .pipe(uglify())
    .pipe(gulp.dest('dist'));
});

Handling Errors

This feature demonstrates how to handle errors during the minification process. By using the 'gulp-plumber' package, you can prevent the Gulp process from stopping when an error occurs, allowing for smoother development workflows.

const gulp = require('gulp');
const uglify = require('gulp-uglify');
const plumber = require('gulp-plumber');

gulp.task('minify-js', function() {
  return gulp.src('src/*.js')
    .pipe(plumber())
    .pipe(uglify())
    .pipe(gulp.dest('dist'));
});

Source Maps

This feature allows you to generate source maps for the minified JavaScript files. Source maps help in debugging by mapping the minified code back to the original source code. The code sample shows how to initialize source maps, minify the JavaScript files, and write the source maps to the output directory.

const gulp = require('gulp');
const uglify = require('gulp-uglify');
const sourcemaps = require('gulp-sourcemaps');

gulp.task('minify-js', function() {
  return gulp.src('src/*.js')
    .pipe(sourcemaps.init())
    .pipe(uglify())
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest('dist'));
});

Other packages similar to gulp-uglify

terser

Terser is a JavaScript parser and mangler/compressor toolkit for ES6+. It is a popular alternative to UglifyJS and is known for its better support for modern JavaScript syntax. Terser can be used with Gulp through the 'gulp-terser' plugin, offering similar functionalities to gulp-uglify but with improved ES6+ support.

babel-minify

Babel-Minify is a minifier based on the Babel toolchain. It is designed to work seamlessly with Babel, making it a good choice for projects that already use Babel for transpiling. Babel-Minify can be integrated with Gulp using the 'gulp-babel-minify' plugin, providing an alternative to gulp-uglify with better integration for Babel users.

uglify-es

Uglify-ES is a fork of UglifyJS that adds support for ES6+ syntax. It is no longer actively maintained, but it was created to address the need for minifying modern JavaScript code. While gulp-uglify does not support ES6+ syntax, Uglify-ES can be used with Gulp through the 'gulp-uglify-es' plugin for projects that require ES6+ support.

README

gulp-uglify

Minify JavaScript with UglifyJS2.

Installation

Install package with NPM and add it to your development dependencies:

npm install --save-dev gulp-uglify

Usage

var gulp = require('gulp');
var uglify = require('gulp-uglify');
var pump = require('pump');

gulp.task('compress', function (cb) {
  pump([
        gulp.src('lib/*.js'),
        uglify(),
        gulp.dest('dist')
    ],
    cb
  );
});

To help properly handle error conditions with Node streams, this project recommends the use of pump. For more information, see Why Use Pump?.

Options

• mangle

  Pass false to skip mangling names.

• output

  Pass an object if you wish to specify additional output options. The defaults are optimized for best compression.

• compress

  Pass an object to specify custom compressor options. Pass false to skip compression completely.

• preserveComments

  A convenience option for options.output.comments. Defaults to preserving no comments.

  • all

    Preserve all comments in code blocks

  • license

    Attempts to preserve comments that likely contain licensing information, even if the comment does not have directives such as @license or /*!.

    Implemented via the uglify-save-license module, this option preserves a comment if one of the following is true:

    1. The comment is in the first line of a file
    2. A regular expression matches the string of the comment. For example: MIT, @license, or Copyright.
    3. There is a comment at the previous line, and it matches 1, 2, or 3.

  • function

    Specify your own comment preservation function. You will be passed the current node and the current comment and are expected to return either true or false.

  • some (deprecated)

    Preserve comments that start with a bang (!) or include a Closure Compiler directive (@preserve, @license, @cc_on). Deprecated in favor of the license option, documented above.

You can also pass the uglify function any of the options listed here to modify UglifyJS's behavior.

Errors

gulp-uglify emits an 'error' event if it is unable to minify a specific file. The GulpUglifyError constructor is exported by this plugin for instanceof checks. It contains the following properties:

• fileName: The full file path for the file being minified.
• cause: The original UglifyJS error, if available.

Most UglifyJS error messages have the following properties:

• message (or msg)
• filename
• line

To see useful error messages, see Why Use Pump?.

Using a Different UglifyJS

By default, gulp-uglify uses the version of UglifyJS installed as a dependency. It's possible to configure the use of a different version using the "minifier" entry point.

var uglifyjs = require('uglify-js'); // can be a git checkout
                                     // or another module (such as `uglify-js-harmony` for ES6 support)
var minifier = require('gulp-uglify/minifier');
var pump = require('pump');

gulp.task('compress', function (cb) {
  // the same options as described above
  var options = {
    preserveComments: 'license'
  };

  pump([
      gulp.src('lib/*.js'),
      minifier(options, uglifyjs),
      gulp.dest('dist')
    ],
    cb
  );
});