js 判断当前的手机系统类型

<script language="javascript">
window.onload = function () {
alert("1");
var u = navigator.userAgent;
if (u.indexOf('Android') > -1 || u.indexOf('Linux') > -1) {//安卓手机
alert("安卓手机");
// window.location.href = "mobile/index.html";
} else if (u.indexOf('iPhone') > -1) {//苹果手机
// window.location.href = "mobile/index.html";
alert("苹果手机");
} else if (u.indexOf('Windows Phone') > -1) {//winphone手机
alert("winphone手机");
// window.location.href = "mobile/index.html";
}
}
</script>