1、相关接口：    var url ="https://api.mch.weixin.qq.com/pay/orderquery";

2、接口参数：

let formData = "<xml>";

formData += "<appid>" + 'wxd3c1c2cc4b2946b4' + "</appid>";

formData += "<mch_id>" + '1585826731' + "</mch_id>";

formData += "<nonce_str>" + 've73xtcjOGgYPr9J123' + "</nonce_str>";

    formData += "<transaction_id>" + '4200000938202104126155956086' + "</transaction_id>";

formData += "<sign>" + 'E5F0BAAFA**************5380DB2F10' + "</sign>"; //sign是在https://pay.weixin.qq.com/wiki/tools/signverify/手动产生的;

formData += "</xml>";

编译结果：