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Static scope analysis and transpilation of ES6 block scoped const and let variables, to ES3.
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Static scope analysis and transpilation of ES6 block scoped const and let variables, to ES3

Build Status Build status Built with Grunt

NOTE: grunt-defs is no longer developed similarly to the underlying defs package. Use Babel or Typescript with their Grunt plugins; they do so much more.

Getting Started

This plugin requires Grunt.

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-defs --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:


The "defs" task


In your project's Gruntfile, add a section named defs to the data object passed into grunt.initConfig().

  defs: {
    options: {
      // Task-specific options go here.
    your_target: {
      // Target-specific file lists and/or options go here.


The defs task accepts a couple of options:

    // Here one can set `defs` options; see:
    defsOptions: {
        disallowDuplicated: true,
        disallowUnknownReferences: false,
        disallowVars: true,

    // Instead of providing `defsOptions` manually, one can provide a URL to the `defs-config.json`
    // configuration file; see:
    defsConfigUrl: string,

Usage Examples

    defs: {
        options: {
            defsConfigURL: 'defs-config.json',
        app1: {
            files: {
                'a.js': ['a.js'],
                'c.js': ['b.js'],
                'f.js': ['d.js', 'e.js'],
        app2: {
            files: [
                    expand: true,
                    src: ['f.js'],
                    ext: '.defs.js', // Dest filepaths will have this extension.
                    extDot: 'last',  // Extensions in filenames begin after the last dot
        app3: {
            files: [
                    expand: true,
                    src: ['g.js'],
                    rename: function (dest, src) { return src + '-defs'; },


After executing grunt defs, you'll get file a.js transformed and saved under the same name, file b.js transformed and saved as c.js and files d.js and e.js concatenated, transformed and saved as f.js.

A transformed version of the f.js file will be saved as f.defs.js and a transformed version of the g.js file will be saved as g.js-defs.

Supported Node.js versions

This project aims to support all Node.js LTS versions in the "active" phase (see LTS README for more details) as well as the latest stable Node.js.

Because of the popularity of this package and Node.js 0.10, this version is temporarily supported as well.


In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

(Nothing yet)


Copyright (c) 2014 Laboratorium EE. Licensed under the MIT license.

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