//获取url中指定参数
function getParam(name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");
    var URL = decodeURI(window.location.search);
    var r = URL.substr(1).match(reg);
    if (r != null) {
        //decodeURI() 函数可对 encodeURI() 函数编码过的 URI 进行解码
        return decodeURI(r[2]);
    };
    return null;
}
console.log(getParam(‘aaa‘));