uglify-examples.md

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 reserved array in the mangle options.

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

Source maps

Generate a source map by setting the sourceMap option to true. The generated source map will be in the same directory as the destination file. Its name will be the basename of the destination file with a .map extension. Override these defaults with the sourceMapName attribute.

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

Advanced source maps

Set the sourceMap.includeSources option to true to embed your sources directly into the map. To include a source map from a previous compilation pass it as the value of the sourceMapIn option.

// Project configuration.
grunt.initConfig({
  uglify: {
    my_target: {
      options: {
        sourceMap: {
          includeSources: true
        },
        sourceMapIn: 'example/coffeescript-sourcemap.js', // input sourcemap from a previous compilation
      },
      files: {
        'dest/output.min.js': ['src/input.js'],
      },
    },
  },
});

Refer to the UglifyJS SourceMap Documentation for more information.

Turn off console warnings

Specify drop_console: true as part of the compress options to discard calls to console.* functions. This will suppress warning messages in the console.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      compress: {
        drop_console: true
      }
    },
    my_target: {
      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.

See UglifyJS documentation for more information.

// 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
        }
      },
      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. This is equivalent to the command line --define option.

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'
      }]
    }
  }
});

Compiling all files separately in the each their path

This configuration will compress and mangle all js files separately in each folder.

Also exclude jQuery for mangling and ignore all *.min.js files.

// Project configuration.
uglify: {
  dev: {
    options: {
      mangle: {
        reserved: ['jQuery']
      }
    },
    files: [{
      expand: true,
      src: ['dist/assets/js/*.js', '!dist/assets/js/*.min.js'],
      dest: 'dist/assets',
      cwd: '.',
      rename: function (dst, src) {
        // To keep the source js files and make new files as `*.min.js`:
        // return dst + '/' + src.replace('.js', '.min.js');
        // Or to override to src:
        return src;
      }
    }]
  }
},

Turn on object property name mangling

This configuration will turn on object property name mangling, but not mangle built-in browser object properties. Additionally, variables and object properties listed in the myExceptionsFile.json will be mangled. For more info, on the format of the exception file format please see the UglifyJS docs.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      mangle: {
        properties: true
      },
      reserveDOMProperties: true,
      exceptionsFiles: [ 'myExceptionsFile.json' ]
    },
    my_target: {
      files: {
        'dest/output.min.js': ['src/input.js']
      }
    }
  }
});

Turn on use of name mangling cache

Turn on use of name mangling cache to coordinate mangled symbols between outputted uglify files. uglify will the generate a JSON cache file with the name provided in the options. Note: this generated file uses the same JSON format as the exceptionsFiles files.

// Project configuration.
grunt.initConfig({
  uglify: {
    options: {
      nameCache: '.tmp/grunt-uglify-cache.json',
    },
    my_target: {
      files: {
        'dest/output1.min.js': ['src/input1.js'],
        'dest/output2.min.js': ['src/input2.js']
      }
    }
  }
});