如何使用两个Ajax Get请求仅显示一个警报消息？

如何解决如何使用两个Ajax Get请求仅显示一个警报消息？

我正在使用两个Ajax Get请求，每个请求都有一个if条件，以防万一不适用，我必须保存原因并将其显示在一个警告消息中。但是我正在显示两个警报，每个警报针对一个获取请求。这是我的代码：

    var errorMessage = "";

  $.get(url,function (responseGET) {
    var responseGETHtml = $(responseGET).find(".data-table tbody").html();

    console.log("responseGETHtml",responseGETHtml,typeof responseGETHtml);
    var rowCount = $(responseGETHtml).filter("tr").length;

       if (rowCount > 1) {
      errorMessage +=
        "There is more than one result for invoice #" + invoiceId + "\n";
    }
  });

  var url2 = "/einnahmen/" + customerId;
  url = url2.trim();
  $.get(url2,function (responseGET) {
    var responseGETHtml2 = $(responseGET).find(".data-item-form form.form");
      
  
    if (brutto < csvBrutto) {
      errorMessage += "Brutto of csv is bigger than Brutto in table" + "\n";
    }

    if (errorMessage != "") {
      alert(errorMessage);
    } else {
      responseGETHtml
        .find(".form-choice .forminput-zahlungsweise")
        .prop("checked",true)
        .val("Überweisung");

      $.post({
        url: "/einnahmen/?filter[rechnung_nr]=" + invoiceId,data: responseGETHtml.serialize(),success: function (responsePOST) {
          alert($(responsePOST).find(".message").text());
        },dataType: "html"
      });
    }
  });

我如何只显示一条包含所有错误的警报消息？

解决方法

我的想法是使用Promises，尤其是Promise.all()。

1. 让我们将每个请求转换为一个承诺，该承诺将以errorMessage作为参数来解决请求的结果。
2. 在这些承诺上使用Promise.all（），当两个请求都解决后，新的承诺将得到解决
3. 如果一个或多个请求给出了错误，如果没有恢复您的代码，请加入错误消息

  const request1 = new Promise(resolve => {
    $.get(url,function(responseGET) {
      var responseGETHtml = $(responseGET).find(".data-table tbody").html();

      console.log("responseGETHtml",responseGETHtml,typeof responseGETHtml);
      var rowCount = $(responseGETHtml).filter("tr").length;

      const errorMessage = rowCount > 1 ? `There is more than one result for invoice #${invoiceId}` : '';

      resolve(errorMessage);

    });
  });

  var url2 = "/einnahmen/" + customerId;
  url = url2.trim();
  const request2 = new Promise(resolve => {
    $.get(url2,function(responseGET) {
      var responseGETHtml2 = $(responseGET).find(".data-item-form form.form");

      const errorMessage = brutto < csvBrutto ? 'Brutto of csv is bigger than Brutto in table' : '';

      resolve(errorMessage);

    });
  });

  Promise.all([request1,request2]).then(errorMessages => {

    // this code is executed when both request has resolved

    // has at least one request resolved with an error message ?
    const hasError = errorMessages.some(error => error != '');

    if (hasError) {
      alert(errorMessages.join('\n'));
    } else {

      // this code is executed when both request has resolved with no error.   

      responseGETHtml
        .find(".form-choice .forminput-zahlungsweise")
        .prop("checked",true)
        .val("Überweisung");

      $.post({
        url: "/einnahmen/?filter[rechnung_nr]=" + invoiceId,data: responseGETHtml.serialize(),success: function(responsePOST) {
          alert($(responsePOST).find(".message").text());
        },dataType: "html"
      });
    }


  });