Javascript 运行多个异步函数并等待结果

我正试图为谷歌地图API v3编写一个函数。基本上，我将遍历给定形状的所有多边形点，并通过将每个点传递给PHP函数将数据插入MySQL，将它们添加到数据库中

    function saveSite() {

        // Create an array to hold the individual point saving results
        var submission_Result = [];
        var final_result = true;

        // Get the general properties for this shape
        var shape_ID = selectedShape.ID;
        var shape_Name = document.getElementById("info_name").value;
        var shape_Description = document.getElementById("info_description").value;
        var shape_Type = shapesArray[shape_ID].type;    

        var shape_Points = selectedShape.getPath();

        // Run through all points in the shape and save them
        for (var i = 0; i < shape_Points.length; i++) {
            var curPoint = shape_Points.getAt(i);

            // Prepare the point data to be saved
            var url = pageDir + "phpsqlinfo_addShapeData.php?db=" + database + "&job=" + jobnumber +
                      "&stype=" + shape_Type + "&snumber=" + shape_ID + "&sname=" + encodeURIComponent(shape_Name) + 
                      "&sdesc=" + encodeURIComponent(shape_Description) + "&sseqno=" + i + "&slat=" + curPoint.lat() + "&slng=" + curPoint.lng();

            // Attempt to save the shape data
            downloadUrl(url, function(data, responseCode) {
                if (responseCode == 200 && data.length <= 1) {
                    submission_Result.push(true);
                } else {
                    submission_Result.push(false);
                }
            });
        }

        // Run through all point results and confirm correct submission of points
        for (var i = 0; i < submission_Result.length; i++) {
            if (submission_Result[i] == false) {
                final_result = false;
            }                
        }

        // If all points were successfully saved, tell the user
        if (final_result == true) {
            // All points saved successfully so do something
        } else {
            // Something went wrong and not all points were added so do something else               
        }
    }

函数saveSite（）{
//创建一个数组以保存各个点的保存结果
风险值提交结果=[]；
var最终结果=真；
//获取此形状的常规属性
var shape_ID=selectedShape.ID；
var shape_Name=document.getElementById（“info_Name”）.value；
var shape_Description=document.getElementById（“info_Description”）.value；
变量shape\u Type=shapesArray[shape\u ID]。类型；
var shape_Points=selectedShape.getPath（）；
//遍历形状中的所有点并保存它们
对于（变量i=0；i如果（responseCode==200&&data.length您必须在传递的回调中检查此项
下载URL
，例如：

downloadUrl(url, function(data, responseCode) {
   //...

   if (submission_Result.length === shape_Points.length)
      allResultsReady();
});

如果所有结果都在中，则将调用函数
allResultsReady

使用循环会阻塞整个浏览器窗口，这绝对不是您想要的。
完美，这正是我所需要的，它工作起来很有魅力。异步javascript对我来说还是相当新的，所以仍然习惯于这些怪癖。
downloadUrl(url, function(data, responseCode) {
   //...

   if (submission_Result.length === shape_Points.length)
      allResultsReady();
});