DEPRECATED: This plugin has been blacklisted as it relies on Uglify to concat the files instead of using gulp-concat, which breaks the "It should do one thing" paradigm. When I created this plugin, there was no way to get source maps to work with gulp, however now there is a gulp-sourcemaps plugin that achieves the same goal. gulp-uglifyjs still works great and gives very granular control over the Uglify execution, I'm just giving you a heads up that other options now exist.

Minify multiple JavaScript with UglifyJS2.

This plugin is based off of gulp-uglify but allows you to directly use all of Uglify's options. The main difference between these two plugins is that passing in an array of files (or glob pattern that matches multiple files) will pass that array directly to Uglify. Uglify will handle both concatenating and minifying those files.

Letting Uglify handle the concatenation and minification allows for the generated source map to be able to separate the files in the browser for easier debugging, and it avoids the intermediate step of concat(). Using concat() and then uglify() would result in a source map for the already concatenated file which has the possibility of being quite large, making it hard to find the code you are wanting to debug.

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

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

This will concatenate and minify all files found by public/js/*.js and write it to a file with the same name as the first file found.

uglify([filename], [options])

• filename - optional

  Override the default output filename.

• options - optional

  These options are directly passed to Uglify. Below are some examples of what is available. To see a full list, read UglifyJS's documentation

  • outSourceMap

    (default false) Give a string to be the name of the source map. Set to true and the source map name will be the same as the output file name suffixed with .map.

    Note: if you would like your source map to point to relative paths instead of absolute paths (which you probably will if it is hosted on a server), set the basePath option to be the base of where the content is served.

  • inSourceMap

    If you're compressing compiled JavaScript and have a source map for it, you can use the inSourceMap argument. This can only be used in conjunction with outSourceMap.

  • sourceRoot

    Sets the root location for where the source files should be found

  • mangle

    (default {}) Set to false to skip mangling names. See options for possible key/value pairs.

  • output

    (default null) Pass an Object if you wish to specify additional output options. The defaults are optimized for best compression.

  • compress

    (default {}) Pass an Object to specify custom compressor options. Pass false to skip compression completely.

  • enclose

    (default undefined) Pass an Object to wrap all of the code in a closure with a configurable arguments/parameters list. Each key-value pair in the enclose object is effectively an argument-parameter pair.

  • wrap

    (default undefined) Pass a String to wrap all of the code in a closure. This is an easy way to make sure nothing is leaking. Variables that need to be public exports and global are made available. The value of wrap is the global variable exports will be available as.

  • exportAll

    (default false) Set to true to make all global functions and variables available via the export variable. Only available when using wrap.

To minify multiple files into a 'app.min.js' and create a source map:

gulp.task('uglify', function() {
  gulp.src('public/js/*.js')
    .pipe(uglify('app.min.js', {
      outSourceMap: true
    }))
    .pipe(gulp.dest('dist/js'))
});

To minify multiple files from different paths to 'app.js', but skip mangling and beautify the results:

gulp.task('uglify', function() {
  gulp.src(['public/js/*.js', 'bower_components/**/*.js'])
    .pipe(uglify('app.js', {
      mangle: false,
      output: {
        beautify: true
      }
    }))
    .pipe(gulp.dest('dist/js'))
});