javascript 获取排列后的对象建值

function getSortedParameter (parameterObject){
    let attributes = [];
    parameterObject = parameterObject ? parameterObject:{};
    for(let attr in parameterObject){
        attributes.push(attr);
    }

    attributes.sort();
    let paramStr = "";
    attributes.forEach(element=>{
        paramStr += element + "=" + parameterObject[element] + "&"
    });

    return paramStr;
}

let me = {};
me["body"] = "test";
me["mch_id"] = "10000100";
me["appid"] = "wxd930ea5d5a258f4f";
me["nonce_str"] = "ibuaiVcKdpRxkhJA";

let signStr = getSortedParameter(me);

//signStr:appid=wxd930ea5d5a258f4f&body=test&device_info=1000&mch_id=10000100&nonce_str=ibuaiVcKdpRxkhJA&