Gruntfile.js

/* -----------------------
root
│
├─ index.html
├─ dev
│  ├─ hmtl
│  ├─ images
│  ├─ js
│  └─ less
│
└─ frontend
   ├─ css
   ├─ images
   └─ javascript
----------------------- */

module.exports = function(grunt) {
	grunt.initConfig({

		imagemin: {
			dynamic: {      
				options: {       
					optimizationLevel: 7
				},
				files: [{
					expand: true, 
					cwd: 'dev/images/',
					src: ['*.{png,jpg,gif}'], 
					dest: 'frontend/images/'  
				}]
			}
		},

        less: {
			development: {
				options: {
					compress: true,
					yuicompress: true,
					optimization: 2
				},
				files: {
					"frontend/css/app.min.css": [
						"dev/less/normalize.less",
						"dev/less/app.less"
					]
				}
			}
		},

		htmlmin: {
			dist: {
				options: {
					removeComments: true,
					collapseWhitespace: true
				},
				files: {
					// 'destination': 'source'
					'index.html': 'dev/html/index.html' 
				}
			}
		},
				
		pkg: grunt.file.readJSON('package.json'),
		uglify: {
			dist: {
				options: {
				  banner: '/*! <%= pkg.name %> - v<%= pkg.version %>\n' +
			        '<%= grunt.template.today("yyyy-mm-dd h:MM:ss TT") %> */\n'
				},
				files: {
					'frontend/javascript/app.min.js': [
						'dev/js/jquery-2.1.1.min.js',
						'dev/js/sammy-latest.min.js',
						'dev/js/app.js',
					]
				}
			}
		},	

		watch: {
			styles: {
				files: ['dev/html/*.html', 'dev/less/*.less', 'dev/js/*.js'],
				tasks: ['htmlmin','less','uglify'],
				options: {
					nospawn: true
				}
			}
		}
	});

	grunt.loadNpmTasks('grunt-contrib-imagemin');
	grunt.loadNpmTasks('grunt-contrib-htmlmin');
	grunt.loadNpmTasks('grunt-contrib-uglify');
	grunt.loadNpmTasks('grunt-contrib-less');
	grunt.loadNpmTasks('grunt-contrib-watch');

	grunt.registerTask('default', ['watch']);
	grunt.registerTask('imagize', ['imagemin']);
};