gruntfile.js

module.exports = function(grunt) {

	grunt.initConfig({

		/***************************************/
		/************ CONFIGURATION ************/
		/***************************************/

		paths: grunt.file.readJSON("paths.json"),
		config: {
			build :'<%= paths.build %>',
			dist : '<%= paths.dist %>'
		},
		path : '<%= config[process.argv[2]] %>', // process.argv[2] = current Grunt overall task. Like default, build, etc. Not sub tasks like uglify.

		/***************************************/
		/************* COMMON TASKS ************/
		/***************************************/

		/**** REMOVE OLD CONTENT ****/

		clean: {
			options: {
				force: true
			},
			files: [
				'<%= path %>/**/**/**'
			]
		},

		/**** COPY ALL FILES ****/

		copy: {
			files: {
				expand: true,
				cwd: 'src',
				src: [
					'**/*',
				],
				dest: '<%= path %>' 
			}
		},

		/**** PROCESS AND COPY CSS AND JS ****/

		postcss: {
			options: {
				processors: [
					require('autoprefixer')({browsers: 'last 2 versions'}), // add vendor prefixes 
					require('cssnano')({
						reduceIdents: false,
						discardUnused: false,
						zindex: false
					}) // minify the result
				]
			},
			dist: {
				files: [
					{
						expand: true,
						cwd: '<%= path %>/assets/stylesheets',
						src: ['*.css'],
						dest: '<%= path %>/assets/stylesheets',
					}
				]
			}
		},
		uglify: {
			my_target: {
				files: [
					{
						expand: true,
						cwd: '<%= path %>/assets/scripts',
						src: ['*.js', '!*.min.js'],
						dest: '<%= path %>/assets/scripts',
					}
				]
			}
		},

		/**** WATCH FOR CHANGES TO SOURCE FILES AND RERUN BUILD TASKS ****/

		watch: {
			scripts: {
				files: ['src/**/**/*'],
				tasks: ['clean', 'copy', 'postcss', 'uglify'],
				options: {
					spawn: false,
				},
			} 
		},
	});

	// 2. Where we tell Grunt we plan to use this plug-in.
	grunt.loadNpmTasks('grunt-postcss');
	grunt.loadNpmTasks('grunt-contrib-uglify');
	grunt.loadNpmTasks('grunt-contrib-copy');
	grunt.loadNpmTasks('grunt-contrib-watch');
	grunt.loadNpmTasks('grunt-contrib-clean');

	// 3. Where we tell Grunt what to do when we type "grunt" into the terminal.
	grunt.registerTask('build', ['clean', 'copy', 'postcss', 'uglify', 'watch']);
	grunt.registerTask('dist', ['clean', 'copy', 'postcss', 'uglify']);


};