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This plugin is being deprecated in favor of grunt-closurecompiler, and will be eventually unpublished. Please migrate.

Grunt task for minifying JavaScript files with Google Closure Compiler.

For grunt 0.3, install the latest 0.1.x version. Grunt 0.4 support starts with version 0.2.0.



npm install grunt-gcc

Add to grunt.js:


initConfig task:

gcc: {
    dist: {
        src: ['src/foo.js', 'src/bar.js'],
        dest: 'dist/foobar.min.js'


You can pass options with:

gcc: {
    dist: {
        options: {
            compilation_level: 'ADVANCED_OPTIMIZATIONS'
        src: ['src/foo.js', 'src/bar.js'],
        dest: 'dist/foobar.min.js'


  • WHITESPACE_ONLY : Removes comments, line breaks, unnecessary spaces, and other whitespace.
  • SIMPLE_OPTIMIZATIONS default : Previous plus shortens local variables, function names, and function parameters.
  • ADVANCED_OPTIMIZATIONS : Previous but also for global variables, function names, and function parameters.

For more specific explanation, visit the Closure Compiler Compilation Levels documentation.


Text banner that will be inserted at the beginning of minified file.

gcc: {
    dist: {
        options: {
            banner: '<%= meta.banner %>'
        src: 'src/foo.js',
        dest: 'dist/foobar.min.js'


Minification reporting. Default is false. Can be:

  • false - no reporting
  • min - report original and minified sizes
  • gzip - report original, minified, and minified & gzipped sizes


Pass a path to a source map if you want to create one. The target directory for sourcemap has to exist.

gcc: {
    dist: {
        options: {
            create_source_map: 'dist/'
        src: 'src/foo.js',
        dest: 'dist/foo.min.js'

Rest of the Closure Compiler options as defined in --help

 --charset VAL                          : Input and output charset for all
                                          files. By default, we accept UTF-8 as
                                          input and output US_ASCII
 --compilation_level [WHITESPACE_ONLY   : Specifies the compilation level to
 --compute_phase_ordering               : Runs the compile job many times, then
                                          prints out the best phase ordering
                                          from this run
 --create_name_map_files                : If true, variable renaming and
                                          property renaming map files will be
                                          produced as {binary name}_vars_map.out
                                          and {binary name}_props_map.out. Note
                                          that this flag cannot be used in
                                          conjunction with either variable_map_o
                                          utput_file or property_map_output_file
 --create_source_map VAL                : If specified, a source map file
                                          mapping the generated source files
                                          back to the original source file will
                                          be output to the specified path. The
                                          %outname% placeholder will expand to
                                          the name of the output file that the
                                          source map corresponds to.
 --debug                                : Enable debugging options
 --define (--D, -D) VAL                 : Override the value of a variable
                                          annotated @define. The format is
                                          <name>[=<val>], where <name> is the
                                          name of a @define variable and <val>
                                          is a boolean, number, or a single-quot
                                          ed string that contains no single
                                          quotes. If [=<val>] is omitted, the
                                          variable is marked true
 --externs VAL                          : The file containing javascript
                                          externs. You may specify multiple
 --formatting [PRETTY_PRINT | PRINT_INP : Specifies which formatting options,
 UT_DELIMITER]                          : if any, should be applied to the
                                          output JS. Options: PRETTY_PRINT,
 --help                                 : Displays this message
 --js VAL                               : The javascript filename. You may
                                          specify multiple
 --js_output_file VAL                   : Primary output filename. If not
                                          specified, output is written to stdout
 --jscomp_dev_mode (--dev_mode) [OFF |  : Turns on extra sanity checks
 --jscomp_error VAL                     : Make the named class of warnings an
                                          error. Options:accessControls,
                                          checkRegExp,checkTypes, checkVars,
                                          deprecated, fileoverviewTags,
                                          invalidCasts, missingProperties,
                                          nonStandardJsDocs, strictModuleDepChec
                                          k, undefinedVars, unknownDefines,
 --jscomp_off VAL                       : Turn off the named class of warnings.
                                          Options:accessControls, checkRegExp,ch
                                          eckTypes, checkVars, deprecated,
                                          fileoverviewTags, invalidCasts,
                                          missingProperties, nonStandardJsDocs,
                                          strictModuleDepCheck, undefinedVars,
                                          unknownDefines, visibility
 --jscomp_warning VAL                   : Make the named class of warnings a
                                          normal warning. Options:accessControls
                                          , checkRegExp,checkTypes, checkVars,
                                          deprecated, fileoverviewTags,
                                          invalidCasts, missingProperties,
                                          nonStandardJsDocs, strictModuleDepChec
                                          k, undefinedVars, unknownDefines,
 --logging_level VAL                    : The logging level (standard java.util.
                                          logging.Level values) for Compiler
                                          progress. Does not control errors or
                                          warnings for the JavaScript code
                                          under compilation
 --manage_closure_dependencies          : Automatically sort dependencies so
                                          that a file that goog.provides symbol
                                          X will always come before a file that
                                          goog.requires symbol X. If an input
                                          provides symbols, and those symbols
                                          are never required, then that input
                                          will not be included in the compilatio
 --module VAL                           : A javascript module specification.
                                          The format is <name>:<num-js-files>[:[
                                          <dep>,...][:]]]. Module names must be
                                          unique. Each dep is the name of a
                                          module that this module depends on.
                                          Modules must be listed in dependency
                                          order, and js source files must be
                                          listed in the corresponding order.
                                          Where --module flags occur in
                                          relation to --js flags is unimportant
 --module_output_path_prefix VAL        : Prefix for filenames of compiled js
                                          modules. <module-name>.js will be
                                          appended to this prefix. Directories
                                          will be created as needed. Use with
 --module_wrapper VAL                   : An output wrapper for a javascript
                                          module (optional). The format is
                                          <name>:<wrapper>. The module name
                                          must correspond with a module
                                          specified using --module. The wrapper
                                          must contain %s as the code placeholde
 --output_manifest VAL                  : Prints out a list of all the files in
                                          the compilation. If --manage_closure_d
                                          ependencies is on, this will not
                                          include files that got dropped
                                          because they were not required. The
                                          %outname% placeholder expands to the
                                          js output file. If you're using
                                          modularization, using %outname% will
                                          create a manifest for each module.
 --output_wrapper VAL                   : Interpolate output into this string
                                          at the place denoted by the marker
                                          token %output%. See --output_wrapper_m
 --output_wrapper_marker VAL            : Use this token as output marker in
                                          the value of --output_wrapper
 --print_ast                            : Prints a dot file describing the
                                          internal abstract syntax tree and
 --print_pass_graph                     : Prints a dot file describing the
                                          passes that will get run and exits
 --print_tree                           : Prints out the parse tree and exits
 --process_closure_primitives           : Processes built-ins from the Closure
                                          library, such as goog.require(),
                                          goog.provide(), and goog.exportSymbol(
 --property_map_input_file VAL          : File containing the serialized
                                          version of the property renaming map
                                          produced by a previous compilation
 --property_map_output_file VAL         : File where the serialized version of
                                          the property renaming map produced
                                          should be saved
 --summary_detail_level N               : Controls how detailed the compilation
                                          summary is. Values: 0 (never print
                                          summary), 1 (print summary only if
                                          there are errors or warnings), 2
                                          (print summary if type checking is
                                          on, see --check_types), 3 (always
                                          print summary). The default level is 1
 --third_party                          : Check source validity but do not
                                          enforce Closure style rules and
 --use_only_custom_externs              : Specifies whether the default externs
                                          should be excluded
 --variable_map_input_file VAL          : File containing the serialized
                                          version of the variable renaming map
                                          produced by a previous compilation
 --variable_map_output_file VAL         : File where the serialized version of
                                          the variable renaming map produced
                                          should be saved
 --version                              : Prints the compiler version to stderr.
 --warning_level [QUIET | DEFAULT |     : Specifies the warning level to use.
 VERBOSE]                               : Options: QUIET, DEFAULT, VERBOSE

In options that do not accept value, just pass true instead. Also with options that accept multiple values, pass the values in an array to that option:

gcc: {
    dist: {
        options: {
            debug: true, // Simple flag without input value 
            externs: [   // Multiple values 
        src: ...,
        dest: ...