Usage examples

Basic compression

This configuration will compress and mangle the input files using the default options.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      files: {
        'dest/output.min.js': ['src/input1.js', 'src/input2.js']
      }
    }
  }
});

No mangling

Specify mangle: false to prevent changes to your variable and function names.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      mangle: false
    },
    my_target: {
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Reserved identifiers

You can specify identifiers to leave untouched with an except array in the mangle options.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      mangle: {
        except: ['jQuery', 'Backbone']
      }
    },
    my_target: {
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Source maps

Configure basic source map output by specifying a file path for the sourceMap option.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      options: {
        sourceMap: 'path/to/source-map.js'
      },
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Advanced source maps

You can specify the parameters to pass to UglifyJS.SourceMap() which will allow you to configure advanced settings.

Refer to the UglifyJS SourceMap Documentation for more information.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      options: {
        sourceMap: 'path/to/source-map.js',
        sourceMapRoot: 'http://example.com/path/to/src/', // the location to find your original source
        sourceMapIn: 'example/coffeescript-sourcemap.js', // input sourcemap from a previous compilation
      },
      files: {
        'dest/output.min.js': ['src/input.js'],
      },
    },
  },
});

Beautify

Specify beautify: true to beautify your code for debugging/troubleshooting purposes. Pass an object to manually configure any other output options passed directly to UglifyJS.OutputStream().

See UglifyJS Codegen documentation for more information.

Note that manual configuration will require you to explicitly set beautify: true if you want traditional, beautified output.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      options: {
        beautify: true
      },
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    },
    my_advanced_target: {
      options: {
        beautify: {
          width: 80,
          beautify: true
        }
      },
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Banner comments

In this example, running grunt uglify:my_target will prepend a banner created by interpolating the banner template string with the config object. Here, those properties are the values imported from the package.json file (which are available via the pkg config property) plus today's date.

Note: you don't have to use an external JSON file. It's also valid to create the pkg object inline in the config. That being said, if you already have a JSON file, you might as well reference it.

// Project configuration.
grunt.initConfig({
  pkg: grunt.file.readJSON('package.json'),
  uglify: {
    options: {
      banner: '/*! <%= pkg.name %> - v<%= pkg.version %> - ' +
        '<%= grunt.template.today("yyyy-mm-dd") %> */'
    },
    my_target: {
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Conditional compilation

You can also enable UglifyJS conditional compilation. This is commonly used to remove debug code blocks for production builds.

See UglifyJS global definitions documentation for more information.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      compress: {
        global_defs: {
          "DEBUG": false
        },
        dead_code: true
      }
    },
    my_target: {
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Compiling all files in a folder dynamically

This configuration will compress and mangle the files dynamically.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      files: [{
          expand: true,
          cwd: 'src/js',
          src: '**/*.js',
          dest: 'dest/js'
      }]
    }
  }
});