function getCss(curEle,attr) {
        var val = null;
        var reg = null;
        if ("getComputedStyle" in window) {
            val = window.getComputedStyle(curEle, null)[attr];
        }
    else{
            if(attr==="opacity"){
                val=curEle.currentStyle["filter"];
                reg=/^alpha\(opacity=(\d+(?:\.\d+)?\))$/i;
                val=reg.test(val)?reg.exec(val)[1]/100:1;
            }else{
                val=curEle.currentStyle[attr];
            }
        }
        reg=/^(-?\d+(\.\d+)?)(px|pt|rem|em)?$/i;
        return reg.test(val)?parseFloat(val):val;
    }
写的外部js一直在浏览器中报错 为什么呢?
请指点
Uncaught TypeError: Failed to execute 'getComputedStyle' on 'Window': parameter 1 is not of type 'Element'.