获取URL的参数值

getParam.js

function getParam(name, url) {
        var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)');
        if (!url){
            url = window.location.href;
        }
        if(url.indexOf("?") <0){
            return null;
        }
        var query = url.substr(url.indexOf("?"), url.length);
        var r = query.substr(1).match(reg);
        if (r != null)
            return decodeURI(r[2]);
        return null;
    }