js如何区分是IOS还是Android?

var u = navigator.userAgent;
var app = navigator.appVersion;
var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Linux') > -1; //g
var isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端
if(isAndroid) {
console.log('安卓')
}
if(isIOS) {　　　
console.log('IOS')
}