判断设备系统和浏览器

var isMac = /macintosh|mac os x/i.test(navigator.userAgent);
var isWindows = /windows|win32/i.test(navigator.userAgent);
var isAndriod = /andriod/i.test(navigator.userAgent);
var isIos = /(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent);
var isWeChat = /MicroMessenger/i.test(navigator.userAgent);