js：运行设备环境类型判断

/**
* 判断设备类型
*/
function isClient(clientName) {
   return (
       window.navigator.userAgent
           .toLowerCase()
           .indexOf(clientName.toLowerCase()) > -1
   );
}
function isMobile() {
  return window.screen.availWidth < 768;
}
function isIphone() {
   return isClient("iPhone");
}
function isAndroid() {
   return isClient("Android");
}
function isWeixin() {
   return isClient("MicroMessenger");
}
function isWorkWeixin() {
   return isClient("wxwork");
}