JavaScript：js 正则表达式判断 Android、io

if (/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) {
    alert(navigator.userAgent);  
    //苹果端
} else if (/(Android)/i.test(navigator.userAgent)) {
    alert(navigator.userAgent); 
    //安卓端
} else {
   //pc端
};