Minify JavaScript with UglifyJS3.

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

npm install --save-dev gulp-uglify

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?.

Most of the minify options from the UglifyJS API are supported. There are a few exceptions:

1. The sourceMap option must not be set, as it will be automatically configured based on your Gulp configuration. See the documentation for Gulp sourcemaps.

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?.

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 "composer" entry point.

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

var minify = composer(uglifyjs, console);

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

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