Grunt Task for running tasks if source files are newer only


Grunt Task for running tasks if source files are newer only.

This mimics the behaviour of good old Unix build tool make(1) within the Grunt build tool, i.e., destination files are only built if either the destination file is still not existing at all or the corresponding source files are newer. As a result, on subsequent build runs, this allows you to rebuild just those artifacts which are really out-of-date.

It is also a little bit similar to (and even can be combined with) the Grunt watch task (from the grunt-contrib-watch package). But instead of continiously monitoring the filesystem for modifications, this task only checks the modification time (mtime) of the files once.

Notice that there is another Grunt plugin named grunt-newer which provides a similar functionality, but performs its operation implicitly and has to store timestamps to know what has changed between runs. I prefer the more explicit and database-less way as in the old Unix make(1), hence I created this task grunt-newer-explicit.

This plugin requires Grunt ~0.4.0

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-newer-explicit --save-dev

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

  • tasks: (default []) the names of Grunt tasks to run if one of the src files are newer than the dest file (or the dest file is still not existing).

Run this task with the grunt newer command.

Task targets, files and options may be specified according to the Grunt Configuring tasks guide.

module.exports = function (grunt) {
        copy: {
            "foo": { src: "src/foo.txt", dest: "build/foo.txt" },
            "bar": { src: "src/bar.txt", dest: "build/bar.txt" }
        newer: {
            "foo": {
                src: [ "src/foo.txt" ],
                dest: "build/foo.txt",
                options: { tasks: [ "copy:foo" ] }
            "bar": {
                src: [ "src/bar.txt" ],
                dest: "build/bar.txt",
                options: { tasks: [ "copy:bar" ] }
        watch: {
            "all": {
                files: [ "src/*.txt" ],
                tasks: [ "newer" ]
        clean: {
            clean:     [ "build" ],
            distclean: [ "node_modules" ]
    grunt.registerTask("default", [ "newer" ]);