获取当前URL中某个参数值

function getParamByName(paramName) {
    paramValue = "", isFound = !1;
    if (this.location.search.indexOf("?") == 0 && this.location.search.indexOf("=") > 1) {
        arrSource = unescape(this.location.search).substring(1, this.location.search.length).split("&"), i = 0;
        while (i < arrSource.length && !isFound) 
            arrSource[i].indexOf("=") > 0 && arrSource[i].split("=")[0].toLowerCase() == paramName.toLowerCase() && (paramValue =             arrSource[i].split("=")[1], isFound = !0), i++
    }
    paramValue == "" && (paramValue = null), paramValue
    return paramValue;
}