js 判断当前的手机系统类型

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