grunt-closure-tools

1.0.0 verified Fri May 01 auth: no javascript maintenance

Grunt plugin integrating Google Closure Library tools (Compiler, Builder, DepsWriter) for JavaScript minification, dependency calculation, and bundling. Version 1.0.0 (stable, last release 2019) targets Grunt 0.4.x. Supports Closure Compiler jar-based compilation, closurebuilder.py concatenation, and depswriter.py deps generation. Key differentiators: full Closure toolchain integration in Grunt, support for advanced compilation options, and file-level change detection (checkModified). Alternative to gulp-closure-compiler or webpack closure plugins.

Common errors

error Warning: Task "closureCompiler" not found. Use --force to continue. ↓

cause The task was not loaded via grunt.loadNpmTasks('grunt-closure-tools').

fix

Add grunt.loadNpmTasks('grunt-closure-tools'); to your Gruntfile.

error Fatal error: java.io.IOException: Cannot run program "/path/to/closure-compiler.jar": error=2, No such file or directory ↓

cause compilerFile path is incorrect or missing; Java cannot find the jar.

fix

Verify the compilerFile path exists, or use an absolute path. For Windows, ensure forward slashes or escaped backslashes.

error Fatal error: maxBuffer exceeded ↓

cause The output from the compiler command exceeds Node's default buffer size (200KB).

fix

Increase the buffer by setting execOpts: { maxBuffer: 999999 * 1024 } in the task options.

error Warning: DepsWriter: No files found to process. ↓

cause The root directory in depsWriter options does not contain any .js files specified by the includes/excludes.

fix

Ensure the root path is correct and use the includes option (string or array) to specify which files to scan.

Warnings

breaking Grunt 0.4.x migration: Task configuration structure changed. Options must be nested under `options` key, not top-level. ↓

fix Move `compilerFile`, `compilerOpts`, `execOpts` inside `options: {}` block.

deprecated Builder and DepsWriter depend on Python scripts (closurebuilder.py, depswriter.py) which are deprecated by Google. ↓

fix Consider migrating to pure Node alternatives like 'google-closure-compiler' for compilation and manual dependency management.

gotcha compilerFile must point to an actual closure-compiler.jar. If missing, task fails silently or with Java errors. ↓

fix Download compiler.jar from https://dl.google.com/closure-compiler/compiler-latest.zip or use npm package 'google-closure-compiler-java' and set path to its jar.

gotcha Max buffer exceeded: Node default 200*1024 may be insufficient for large files, causing 'Error: maxBuffer exceeded'. ↓

fix Set execOpts.maxBuffer in options, e.g., `execOpts: { maxBuffer: 999999 * 1024 }`.

gotcha File paths with glob patterns (e.g., 'src/**/*.js') must be in src array. The grunt file syntax (<config:...>) is NOT supported in src. ↓

fix Use grunt's usual array of file patterns in src; do not use template syntax like `'<%= pkg.name %>'` in src.

Install

npm install grunt-closure-tools

yarn add grunt-closure-tools

pnpm add grunt-closure-tools

Imports

default (task registration)
wrong
```
require('grunt-closure-tools');
```
correct
```
grunt.loadNpmTasks('grunt-closure-tools');
```
Do not require the module directly; use grunt.loadNpmTasks to register all three multitasks (closureCompiler, closureBuilder, closureDepsWriter).

closureCompiler config

wrong

closureCompiler: { compilerFile: 'compiler.jar' }

correct

closureCompiler: { options: { compilerFile: 'compiler.jar', compilerOpts: { compilation_level: 'ADVANCED_OPTIMIZATIONS' } } }

compilerFile is required inside options, not at top level. Also compilerOpts is an object, not directly at options level.

closureBuilder config

wrong

closureBuilder: { builder: 'closurebuilder.py' }

correct

closureBuilder: { options: { builder: 'closurebuilder.py', root: 'src/', output_mode: 'compiled', compiler: 'compiler.jar' } }

Builder task requires root and compiler option even if not compiling. Output_mode can be 'list', 'script', or 'compiled'.

closureDepsWriter config

wrong

closureDepsWriter: { root: 'src/', deps: 'deps.js' }

correct

closureDepsWriter: { options: { root: 'src/', deps: 'deps.js' } }

root and deps should be inside options, not at top level.

Quickstart

Minimal Gruntfile configuring the Closure Compiler task with a jar path, source files, and simple optimizations.

// Install: npm install grunt-closure-tools --save-dev
// Gruntfile.js
module.exports = function(grunt) {
  grunt.loadNpmTasks('grunt-closure-tools');

  grunt.initConfig({
    closureCompiler: {
      options: {
        compilerFile: 'node_modules/google-closure-compiler-java/compiler.jar',
        checkModified: true,
        compilerOpts: {
          compilation_level: 'SIMPLE_OPTIMIZATIONS',
          warning_level: 'verbose'
        }
      },
      dist: {
        src: ['src/**/*.js'],
        dest: 'dist/bundle.min.js'
      }
    }
  });

  grunt.registerTask('default', ['closureCompiler']);
};