var url_build = function (path, params) {
        var url = "" + path;
        var _paramUrl = "";
        // url 拼接 a=b&c=d
        if(params){
            _paramUrl = Object.keys(params).map(function (k) {
                return [encodeURIComponent(k), encodeURIComponent(params[k])].join("=");
            }).join("&");
            _paramUrl = "?" + _paramUrl
        }
        return url + _paramUrl
    }

解释

1. params 对象形如:{“id”:1, “q”:2}
2. encodeURIComponent 将sring字符串作为URI组件进行编码
3. 拼接成形如http://www.baidu.com/?id=1@q=2的样式