Example (working?) grunt watch task

Gruntfile.js

var settings = require('./settings');
module.exports = function(grunt) {
    grunt.initConfig({
        settings: grunt.file.readJSON('settings.json'),
        pkg: grunt.file.readJSON('package.json'),
        concat: {
            options: {
                banner: '(function () {\n\'use strict\';\n',
                footer: '}());'
            },
            dist: {
                src: ['source/application.js', 'source/modules.js', 'source/dimensions.js', 'source/nav-arrows.js', 'source/ready.js', 'source/content.js'],
                dest: '<%= settings.target %><%= pkg.name %>.js'
            }
        },
        less: {
            development: {
                files: {
                    "<%= settings.target %><%= pkg.name %>.css": "source/<%= pkg.name %>.less"
                }
            },
            production: {
                options: {
                    cleancss: true
                },
                files: {
                    "<%= settings.target %><%= pkg.name %>.min.css": "source/<%= pkg.name %>.less"
                }
            }
        },
        uglify: {
            options: {
                banner: '/*! <%= pkg.description %> v<%= pkg.version %> <%= grunt.template.today("yyyy-mm-dd") %>*/\n'
            },
            build: {
                src: '<%= settings.target %><%= pkg.name %>.js',
                dest: '<%= settings.target %><%= pkg.name %>.min.js'
            }
        },
        watch: {
            options: {
                spawn : false
            },
            css: {
                files: 'source/<%= pkg.name %>.less',
                tasks: 'less'
            },
            scripts: {
                files: 'source/*.js',
                tasks: ['concat', 'uglify']
            }
        },
		newer: {
			options: {
				cache: 'cache'
			}
		}
    });
    
    grunt.loadNpmTasks('grunt-contrib-concat');
    grunt.loadNpmTasks('grunt-contrib-less');
    grunt.loadNpmTasks('grunt-contrib-uglify');
    grunt.loadNpmTasks('grunt-contrib-watch');
    grunt.loadNpmTasks('grunt-newer');
    
    grunt.registerTask('default', ['newer:less', 'newer:concat', 'newer:uglify']);
};