Grunt

gistfile1.js

{
  "name": "sample",
  "version": "0.0.1",
  "description": "grunt sample",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": "",
  "author": "shirokuro331",
  "license": "BSD",
  "devDependencies": {
    "grunt": "~0.4.1",
    "grunt-contrib-compass": "~0.3.0",
    "grunt-contrib-watch": "~0.4.4",
    "grunt-contrib-connect": "~0.3.0",
    "grunt-contrib-cssmin": "~0.6.1",
    "grunt-contrib-imagemin": "~0.1.4",
    "grunt-contrib-concat": "~0.3.0",
    "grunt-contrib-uglify": "~0.2.2"
  }
}

Gruntfile.js

module.exports = function (grunt) {

  grunt.initConfig({
    watch:{
        sassmin:{
          files: 'src/scss/*.scss',
          tasks: ['compass','cssmin']
        },
        js:{
          files: 'src/js/*.js',
          tasks: ['concat']
        },
        jsmin:{
          files: 'js/all.js',
          tasks: ['uglify']
        }
    },
    compass: {
      dist: {
        options: {
          sassDir:'src/scss',
          cssDir:'src/css'
        }
      }
    },
    cssmin:{
      min:{
          files:{
              'src/css/style.min.css':'src/css/style.css'
          }
      }
    },
    concat: {
      js: {
        src: [
          'src/js/*.js',
        ],
        dest: 'js/all.js'
      }
    },
    uglify: {
      dist: {
        src: 'js/all.js',
        dest: 'js/all.min.js'
      }
    },
    imagemin : {
      dist : {
        options: {
          optimizationLevel: 3
        },
        files : [
          {
            expand : true,
            src: 'img/*.{png,jpg,jpeg}'
          }
        ]
      }
    }
  });

  grunt.loadNpmTasks('grunt-contrib-compass');
  grunt.loadNpmTasks('grunt-contrib-cssmin');
  grunt.loadNpmTasks('grunt-contrib-concat');
  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks("grunt-contrib-watch");
  grunt.loadNpmTasks('grunt-contrib-imagemin');

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