js determined mobile terminal PC logs introduce different css and js

function browserRedirect() {
        var sUserAgent = navigator.userAgent.toLowerCase();
        var bIsIpad = sUserAgent.match(/ipad/i) == "ipad";
        var bIsIphoneOs = sUserAgent.match(/iphone os/i) == "iphone os";
        var bIsMidp = sUserAgent.match(/midp/i) == "midp";
        var bIsUc7 = sUserAgent.match(/rv:1.2.3.4/i) == "rv:1.2.3.4";
        var bIsUc = sUserAgent.match(/ucweb/i) == "ucweb";
        var bIsAndroid = sUserAgent.match(/android/i) == "android";
        var bIsCE = sUserAgent.match(/windows ce/i) == "windows ce";
        var bIsWM = sUserAgent.match(/windows mobile/i) == "windows mobile";
        // document.writeln("您的浏览设备为：");  
        if(bIsIpad || bIsIphoneOs || bIsMidp || bIsUc7 || bIsUc || bIsAndroid || bIsCE || bIsWM) {
            // alert("手机浏览！");  
            document.write('<meta name="viewport" content="width=device-width, initial-scale=1,maximum-scale=1,user-scalable=no">');
            document.write('<link rel="stylesheet" href="css/IndexYD.css" />');
            document.write('<script type="text/javascript" charset="utf-8" src="js/IndexYD.js"><\/script>');
        } else {

            // alert("PC浏览！");  
            document.write('<link rel="stylesheet" href="css/IndexPC.css" />');
            document.write('<script type="text/javascript" charset="utf-8" src="js/IndexPC.js"><\/script>');
        }
    }
    browserRedirect();