获取url中的参数

function getUrlParam(name) {
 ?var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");
 ?var r = window.location.search.substr(1).match(reg);
 ?if (r != null) return unescape(r[2]);
 ?return null;
}

var open_id = getUrlParam(‘open_id‘);