Sample Gruntfile.js to watch CSS/JS/PHP files for updates, concatenate and livereload them on a browser.

Gruntfile.js

/*!
 * [Enter your project name] Gruntfile
 * http://example.com
 * @author Shane Perera
 */

'use strict';

/**
 * Grunt Module
 */
module.exports = function(grunt) {

  /**
   * Configuration
   */
  grunt.initConfig({

    /**
     * Get package meta data
     */
    pkg: grunt.file.readJSON('package.json'),

    /**
     * Set project object
     */
    project: {
      app: 'app',
      assets: 'public',
      css: [
        '<%= project.assets %>/sass/starter-template.scss'
      ],
      js: [
        '<%= project.assets %>/js/*.js'
      ]
    },

    /**
     * Project banner
     */
    tag: {
      banner: '/*!\n' +
              ' * <%= pkg.name %>\n' +
              ' * <%= pkg.title %>\n' +
              ' * <%= pkg.url %>\n' +
              ' * @author <%= pkg.author %>\n' +
              ' * @version <%= pkg.version %>\n' +
              ' * Copyright <%= pkg.copyright %>. <%= pkg.license %> licensed.\n' +
              ' */\n'
    },

    /**
     * Sass
     */
    sass: {
      dev: {
        options: {
          style: 'expanded'
        },
        files: {
          '<%= project.assets %>/css/style.css': '<%= project.css %>'
        }
      },
      dist: {
        options: {
          style: 'compressed'
        },
        files: {
          '<%= project.assets %>/css/style.css': '<%= project.css %>'
        }
      }
    },


    concat: {
      dev: {
        src: ['<%= project.assets %>/js/backbone/src/**/*.js'],
        dest: '<%= project.assets %>/js/backbone/dist/app.js'
      }
    },

    jshint: {
      beforeconcat: ['<%= project.assets %>/js/backbone/src/**/*.js'],
      afterconcat: ['<%= project.assets %>/js/backbone/dist/app.js']
    },

    /**
     * CSSMin
     * CSS minification
     * https://github.com/gruntjs/grunt-contrib-cssmin
     */
    // cssmin: {
    //   dev: {
    //     files: {
    //       'public/css/style.min.css': [
    //         '<%= project.assets %>/bower/normalize-css/normalize.css',
    //         'public/css/style.css'
    //       ]
    //     }
    //   },
    //   dist: {
    //     options: {
    //       banner: '<%= tag.banner %>'
    //     },
    //     files: {
    //       'public/css/style.min.css': [
    //         '<%= project.assets %>/bower/normalize-css/normalize.css',
    //         'public/css/style.css'
    //       ]
    //     }
    //   }
    // },

    /**
     * Watch
     */
    watch: {
      sass: {
        files: '<%= project.assets %>/sass/{,*/}*.{scss,sass}',
        // tasks: ['sass:dev', 'cssmin:dev']
        tasks: ['sass:dev'],
        options: {
          livereload: true
        }
      },
      js: {
        files: '<%= project.assets %>/js/backbone/src/**/*.js',
        tasks: ['jshint:beforeconcat', 'concat:dev', 'jshint:afterconcat'],
        options: {
          livereload: true
        }
      },
      project: {
        files: ['app/views/**/*.blade.php', 'app/controllers/**/*.php'],
        options: {
          livereload: true
        }
      },
    }

  });

  /**
   * Load Grunt plugins
   */
  require('matchdep').filterDev('grunt-*').forEach(grunt.loadNpmTasks);

  /**
   * Default task
   * Run `grunt` on the command line
   */
  grunt.registerTask('default', [
    'sass:dev',
    'jshint:beforeconcat',
    'concat:dev',
    // 'cssmin:dev',
    'watch'
  ]);

  /**
   * Build task
   * Run `grunt build` on the command line
   * Then compress all JS/CSS files
   */
  grunt.registerTask('build', [
    'sass:dist'
  ]);

};