js method to determine mobile browser operating system and WeChat browser_javascript skills

<script type="text/javascript">
//手机端判断各个平台浏览器及操作系统平台
function checkPlatform(){
    if(/android/i.test(navigator.userAgent)){
        document.write("This is Android&#39;browser.");//这是Android平台下浏览器
    }
    if(/(iPhoneiPadiPodiOS)/i.test(navigator.userAgent)){
        document.write("This is iOS&#39;browser.");//这是iOS平台下浏览器
    }
    if(/Linux/i.test(navigator.userAgent)){
        document.write("This is Linux&#39;browser.");//这是Linux平台下浏览器
    }
    if(/Linux/i.test(navigator.platform)){
        document.write("This is Linux operating system.");//这是Linux操作系统平台
    }
    if(/MicroMessenger/i.test(navigator.userAgent)){
        document.write("This is MicroMessenger&#39;browser.");//这是微信平台下浏览器
    }
}
 $(document).ready(function(){
  alert(navigator.platform);
  checkPlatform();
 });
</script>

<script type="text/javascript">
var browser = {
    versions : function () {
        var u = navigator.userAgent,
        app = navigator.appVersion;
        return {
            trident : u.indexOf(&#39;Trident&#39;) > -1,
            presto : u.indexOf(&#39;Presto&#39;) > -1,
            webKit : u.indexOf(&#39;AppleWebKit&#39;) > -1,
            gecko : u.indexOf(&#39;Gecko&#39;) > -1 && u.indexOf(&#39;KHTML&#39;) == -1,
            mobile : !!u.match(/AppleWebKit.*Mobile.*/) || !!u.match(/AppleWebKit/),
            ios : !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),
            android : u.indexOf(&#39;Android&#39;) > -1 || u.indexOf(&#39;Linux&#39;) > -1,
            iPhone : u.indexOf(&#39;iPhone&#39;) > -1 || u.indexOf(&#39;Mac&#39;) > -1,
            iPad : u.indexOf(&#39;iPad&#39;) > -1,
            webApp : u.indexOf(&#39;Safari&#39;) == -1,
            QQbrw : u.indexOf(&#39;MQQBrowser&#39;) > -1,
            weiXin : u.indexOf(&#39;MicroMessenger&#39;) > -1,
            ucLowEnd : u.indexOf(&#39;UCWEB7.&#39;) > -1,
            ucSpecial : u.indexOf(&#39;rv:1.2.3.4&#39;) > -1,
            ucweb : function () {
                try {
   return parseFloat(u.match(/ucweb\d+\.\d+/gi).toString().match(/\d+\.\d+/).toString()) >= 8.2
                } catch (e) {
                    if (u.indexOf(&#39;UC&#39;) > -1) {
                        return true;
                    } else {
                        return false;
                    }
                }
            }
            (),
            Symbian : u.indexOf(&#39;Symbian&#39;) > -1,
            ucSB : u.indexOf(&#39;Firefox/1.&#39;) > -1
        };
    }
    ()
}
if (browser.versions.QQbrw){
document.write("qq浏览器");
}else
{
document.write("其它浏览器");
}
</script>