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
  );
});