Detect features and devices via JavaScript

detection.js

// Engine/OS
var is_iPhone = navigator.platform.indexOf('iPhone') >= 0;
var is_iPad = navigator.platform.indexOf('iPad') >= 0;
var is_iOS = this.is_iPhone || this.is_iPad;
var is_iOS5 = this.is_iOS && window.navigator.appVersion.indexOf('OS 5_') >= 0;
var is_webkit = 'webkitRequestAnimationFrame' in window;
var is_win = navigator.appVersion.indexOf("Win") >= 0;
var is_mac = navigator.appVersion.indexOf("Mac") >= 0;

// Features
var is_touchDevice = ('ontouchstart' in window) || (navigator.msMaxTouchPoints > 0);
var is_html5video = typeof HTMLVideoElement !== 'undefined';
var is_html5audio = typeof HTMLAudioElement !== 'undefined';
var is_html5canvas = typeof HTMLCanvasElement  !== 'undefined';
var is_retina = window.devicePixelRatio > 1;