運行多個異步函數並等待結果

我正在嘗試爲Google Maps API v3編寫一個函數。基本上，我循環遍歷給定形狀的所有多邊形點，並通過將每個點傳遞給將數據插入MySQL的PHP函數將它們添加到數據庫中。運行多個異步函數並等待結果

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    
     } 
    }

我知道* downloadURL *運行作爲異步函數，因此我目前無法通過的* submission_result *陣列循環，並檢查是否正確添加了所有點。我的問題是，有沒有什麼辦法可以等待所有的異步調用完成，然後檢查結果數組？

也許這樣的事情，例如?:

     }); 
     } 

     while (submission_Result.length < shape_Points.length) { 
      // Do something wait a short while 
     }; 

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

任何想法，將不勝感激爲我完全難倒！

在此先感謝。

來源

2012-02-23 JohnHenry

你必須通過downloadUrl回調檢查此，例如：

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

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

如果所有的結果都在，功能allResultsReady將被調用。

使用循環將阻止整個瀏覽器窗口，這絕對不是你想要的。

來源

2012-02-23 09:00:09 Matthias

完美，這就是我所需要的，它就像一個魅力。異步JavaScript對我來說還是比較新的，所以還是習慣了這些怪癖。 – JohnHenry 2012-02-23 09:16:24

運行多個異步函數並等待結果

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