js判断用户手机是IOS还是Android

let u = navigator.userAgent, app = navigator.appVersion;
let isAndroid = u.indexOf('Android') > -1 || u.indexOf('Linux') > -1; //安卓机！
let isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端.
if (isAndroid) {
  　　alert("安卓机！")
}
if (isIOS) {
     alert("苹果果机！")
}