web写750的移动端

<script type="text/javascript">//手机端适应代码
    var mengvalue = -1;
    //if(mengvalue<0){mengvalue=0;}
    var phoneWidth = parseInt(window.screen.width);
    var phoneScale = phoneWidth / 750;
    var ua = navigator.userAgent;
    if (/Android (\d+\.\d+)/.test(ua)) {
        var version = parseFloat(RegExp.$1);
        // andriod 2.3
        if (version > 2.3) {
            document.write('<meta name="viewport" content="width=750, minimum-scale=' + phoneScale + ', maximum-scale=' + phoneScale +', target-densitydpi=device-dpi">');
            // andriod 2.3以上
        } else {
            document.write('<meta name="viewport" content="width=750, target-densitydpi=device-dpi">');
        }
        // 其他系统
    } else {
        document.write('<meta name="viewport" content="width=750, user-scalable=no, target-densitydpi=device-dpi">');
    }
</script>

拿着去改。不行找人工智能