Grunt for minify javascript files

Gruntfile.js

module.exports = function(grunt) {
  grunt.initConfig({
    uglify: {
      options: {
        banner: '/*! application.js <%= grunt.template.today("yyyy-mm-dd hh:MM") %> */\n',
      },
      build: {
        src: 'public/assets/application.min.js',
        dest: 'public/assets/application.min.js'
      }
    }
  });

  // Load the plugin that provides the "uglify" task.
  grunt.loadNpmTasks('grunt-contrib-uglify');

  // Default task(s).
  grunt.registerTask('default', ['uglify']);
};