My Gruntfile.js sample template

Grintfile.js

module.exports = function (grunt) {

    "use strict";

    // requirements
    var fs = require('fs');
    var glob = require("glob");
    var argv = require('yargs').argv;
    var mkdirp = require('mkdirp');

    // helpers
    String.prototype.format = function() {
        var pattern = /\{\d+\}/g;
        var args = arguments;
        return this.replace(pattern, function(capture){ return args[capture.match(/\d+/)]; });
    };

    var BUILD_CONFIG = {
        prod: argv.watch ? false : argv.prod,
        watch: argv.watch || process.env.GRUNT_WATCH,
        src_dir: 'websrc/',
        dist_dir: 'webapp/',
        js_bundles: [ // add here your path/to/, and path/to/main.js will be bundled
            "js/"
        ],
        linting_files: {
            js: [
                "js/"
            ],
            css: [
                "css/"
            ]
        }
    };

    grunt.log.writeln(String("Building {0} to {1} dir in {2} mode".format(
        BUILD_CONFIG.src_dir,
        BUILD_CONFIG.dist_dir,
        BUILD_CONFIG.watch ? "watch" : BUILD_CONFIG.prod ? "production" : "debug"
    )).green);

    // show statistics after build
    if (!argv.watch) {
        require('time-grunt')(grunt);
    }

    // legacy tasks
    require('load-grunt-tasks')(grunt);

    // custom tasks
    grunt.registerMultiTask('myCustomTask', 'myCustomTask description', function() {
        this.files.forEach(function(f) {
            // process
        });
        grunt.log.writeln(String("myCustomTask success").green);
    });

    var GRUNT_CONFIG = {
        pkg: grunt.file.readJSON("package.json"),  
        clean: { // clean dist directory
            prebuild: {
                src: [BUILD_CONFIG.dist_dir]
            },
            main: {
                src: [
                    BUILD_CONFIG.dist_dir + "**/*.js", 
                    BUILD_CONFIG.dist_dir + "**/*.css", 
                    BUILD_CONFIG.dist_dir + "**/*.html"
                ]            
            }
        },            
        less: { // compile all LESS to dist dir
            targetname: {
                expand: true,
                cwd: BUILD_CONFIG.src_dir,
                src: ['**/*.less'],
                dest: BUILD_CONFIG.dist_dir,
                ext: '.css',
                options: {              
                    plugins: [
                        new (require('less-plugin-autoprefix'))()
                    ]
                    
                }
            }
        },
        copy: { // copy all rest non-compilable files
            other: {
                files: [{
                    expand: true,
                    cwd: BUILD_CONFIG.src_dir,
                    src: ['**/*', '!**/*.less', '!**/*.js'],
                    dest: BUILD_CONFIG.dist_dir
                }]
            }
        },              
        uglify: { // minify all scripts
            base: {
                options: {
                    compress: {
                        unused : false
                    }
                },
                files: [{
                    expand: !0,
                    src: [BUILD_CONFIG.dist_dir + "**/*.js"]
                }]
            }
        },
        eslint: { // lint all non-third-party code
            files: BUILD_CONFIG.linting_files.js.map(function(file) {
                return BUILD_CONFIG.src_dir + file;
            }),
            options: {
                configFile: '.eslintrc'
            }
        },
        compress: { // gzip all files
            main: {
                options: {
                    mode: 'gzip'
                },
                files: [
                    {
                        expand: true,
                        cwd: BUILD_CONFIG.dist_dir,
                        src: ['**/*.js'],
                        dest: BUILD_CONFIG.dist_dir,
                        ext: '.js.gz'
                    },
                    {
                        expand: true,
                        cwd: BUILD_CONFIG.dist_dir,
                        src: ['**/*.css'],
                        dest: BUILD_CONFIG.dist_dir,
                        ext: '.css.gz'
                    },
                    {
                        expand: true,
                        cwd: BUILD_CONFIG.dist_dir,
                        src: ['**/*.html'],
                        dest: BUILD_CONFIG.dist_dir,
                        ext: '.html.gz'
                    }
                ]               
            }
        },
        browserify: {  
            // bundling all main.js files, see below 
        },
        watch: { // watching all newer compilable files
            styles_dist: {
                files: BUILD_CONFIG.dist_dir + "**/*.css",
                options: {
                    livereload: true // not needed on css
                }
            },
            styles_src: {
                files: BUILD_CONFIG.src_dir + "**/*.less",
                tasks: ['newer:less'],
                options: {
                    livereload: false
                }
            },
            jslint: {
                files: BUILD_CONFIG.linting_files.js.map(function(file) {
                    return BUILD_CONFIG.src_dir + file;
                }),
                tasks: ['newer:eslint'],
            },
            copy_dry: {
                files: [BUILD_CONFIG.src_dir + 'dry/**/*.js'],
                tasks: ['newer:copy:dry'],
                options: {
                    livereload: true,
                    livereloadOnError: false
                },
            },
            copy_other: {
                files: [
                    BUILD_CONFIG.src_dir + '**/*', 
                    "!" + BUILD_CONFIG.src_dir + '**/*.less', 
                    "!" + BUILD_CONFIG.src_dir + '**/*.js'
                ],
                tasks: ['newer:copy:other'],
                options: {
                    livereload: true,
                    livereloadOnError: false
                },
            },
            browserify: {
                files: BUILD_CONFIG.js_bundles.map(function(path) {
                    return BUILD_CONFIG.dist_dir + path + "main.js"
                }),
                options: {
                    livereload: true
                }
            }
        }
    };

    // add browserify bundles and watch for them support
    BUILD_CONFIG.js_bundles.forEach(function(bundle) {
        GRUNT_CONFIG.browserify[bundle] = {
            src: BUILD_CONFIG.src_dir + bundle + "main.js",
            dest: BUILD_CONFIG.dist_dir + bundle + "main.js",
            options: {
                transform: ['babelify'],
                browserifyOptions: {
                    debug: BUILD_CONFIG.prod ? false : true
                },
                watch: BUILD_CONFIG.watch ? true : false // this will launch live-reload of browserify bundles, but only if task "watch" is active
            }
        };
    });

    grunt.initConfig(GRUNT_CONFIG);

    var tasks = ["clean:prebuild", "less", "eslint", "browserify", "copy","concat"];

    if (BUILD_CONFIG.prod) {
        tasks = tasks.concat(["uglify", "create_cache", "compress", "clean:main"]);
    } else if (BUILD_CONFIG.watch) {
        tasks.push("watch");
    }
    grunt.registerTask("default", tasks);
};