Javascript 在继续循环之前，请等待带有异步调用的函数完成

我正在try 同步日历，但接收服务器只想要"一口大小"的数据，所以我决定每月同步每个用户.

因此，我做了一个双循环:

首先，我循环遍历所有用户，如果日期范围跨越多个月，则在该循环中循环遍历月份.

但是，因为同步函数是异步的，所以它同时执行多个资源和月份，因为循环不等待完成.

我知道以前也有人问过类似的问题，但出于某种原因，我就是不能让它起作用.

以下是我的功能:

function loopThroughMonths(resourceIds, startDate, endDate) {
  startDateObject = new Date(startDate);
  endDateObject = new Date(endDate);

  // Check how many months our date range spans:

  var dateRangeMonths = monthDiff(startDateObject, endDateObject);

  if (dateRangeMonths > 0) {
    // Loop through each month

    for (let i = 0; i <= dateRangeMonths; i++) {
      if (i == 0) {
        // For the first month, the starting date is equal to the start of the date range

        var loopStartDate = startDate;
        var loopEndDate = formatDate(
          lastDayOfMonth(
            startDateObject.getFullYear(),
            startDateObject.getMonth(),
          ),
        );
      }

      if (i != 0 && i != dateRangeMonths) {
        var loopMonth = new Date(
          startDateObject.getFullYear(),
          startDateObject.getMonth() + i,
          1,
        );
        var loopStartDate = formatDate(
          firstDayOfMonth(loopMonth.getFullYear(), loopMonth.getMonth()),
        );
        var loopEndDate = formatDate(
          lastDayOfMonth(loopMonth.getFullYear(), loopMonth.getMonth()),
        );
      }

      if (i == dateRangeMonths) {
        // For the last month, the end date is equal to the last date of the date range.

        var loopStartDate = formatDate(
          firstDayOfMonth(
            endDateObject.getFullYear(),
            endDateObject.getMonth(),
          ),
        );
        var loopEndDate = endDate;
      }

      loopThroughResources(resourceIds, 0, loopStartDate, loopEndDate);
    }
  } else {
    // Date range falls within 1 month, just proceed to looping through resources

    loopThroughResources(resourceIds, 0, startDate, endDate);
  }
}

function loopThroughResources(resourceIds, i, loopStartDate, loopEndDate) {
  if (i == resourceIds.length) {
    $("#start_exchange")
      .text("Synchroniseren")
      .removeAttr("disabled")
      .css("cursor", "pointer");
    return;
  }
  var resourceId = resourceIds[i];

  $("#exchange_output").append(
    "Start synchroniseren naar Outlook-agenda van " +
      resourceNames.get(resourceId) +
      " van " +
      loopStartDate +
      " tot " +
      loopEndDate +
      "...<br>",
  );

  $.post(
    "sync.php",
    {
      resourceId: resourceId,
      startDate: loopStartDate,
      endDate: loopEndDate,
    },
    function (response) {
      $("#exchange_output").append(response);
      i = i + 1;
      loopThroughResources(resourceIds, i, loopStartDate, loopEndDate);
    },
  );
}

因此，我来解释一下:

LoopThroughMonths首先判断startDate和endDate是否相差0个月以上. 如果是这样的话，它每个月都会看一遍.如果不是，它会立即执行loopThroughResources.

如果日期RangeMonth跨越多个月，我们使用for循环遍历它们，并 for each 月执行loopThroughResources函数.

因此，如果我们说:

从2023-12-27到2024-02-16同步资源A、B、C

它将做到:

Sync 2023-12-27 till 2023-12-31 (part of december 2023) for resource A
Sync 2023-12-27 till 2023-12-31 (part of december 2023) for resource B
Sync 2023-12-27 till 2023-12-31 (part of december 2023) for resource C
Sync 2024-01-01 till 2024-01-31 (whole january 2023) for resource A
Sync 2024-01-01 till 2024-01-31 (whole january 2023) for resource B
Sync 2024-01-01 till 2024-01-31 (whole january 2023) for resource C
Sync 2024-02-01 till 2024-02-16 (part of february 2023) for resource A
Sync 2024-02-01 till 2024-02-16 (part of february 2023) for resource B
Sync 2024-02-01 till 2024-02-16 (part of february 2023) for resource C

代码可以工作，但它不会等待所有资源完成(即在loopThroughResources函数完成之前)，然后才继续下个月.

对于资源，我甚至通过从$.post Complete函数调用函数，使其等待资源A的同步完成，然后才继续到资源B，但基本上我需要另一个等待整个loopThroughResources函数(我猜它需要Promiss.all...)

我知道我必须做一些promise ，但我就是不能让它工作. 任何帮助将不胜感激.