Gruntfile.js

module.exports = function(grunt) {

    // Load plugins
    grunt.loadNpmTasks('grunt-manifest');
    grunt.loadNpmTasks('grunt-contrib-watch');

    // Make a list of paths/files to cache
    var cache = ['./public/js/*', './public/img/*', './public/css/*'];

    grunt.initConfig({

        // Define how your manifest file should be constructed
        manifest: {
            generate: {
                options: {
                    network: ['http://*', 'https://*'],
                    timestamp: true
                },
                src: cache,
                dest: 'manifest.appcache'
            }
        },

        // Now setup the watch task to monitor the same files
        // that are referenced in the CACHE section of your
        // manifest, and fire the "manifest" task whenever
        // a change is detected
        watch: {
            scripts: {
                files: cache,
                tasks: ['manifest']
            }
        }
    });

};