jQuery Ajax将画布存储在文件夹中/在服务器上

Question

我对此代码段有疑问：

function upload(){
<!-- grab our drawing data from our myCanvas --> 
var myDrawing = document.getElementById("requiem");
<!-- start our datastring --> 
var drawingString = myDrawing.toDataURL("image/png");
var postData = "canvasData="+drawingString;   
var ajax = new XMLHttpRequest();
<!-- specify our php processing page --> 
ajax.open("POST",'saveImage.php',true);
<!-- set the mime type so the image goes through as base64 --> 
ajax.setRequestHeader('Content-Type', 'canvas/upload');
ajax.onreadystatechange=function(){
     <!-- once the image data has been sent call a simple alert --> 
         if (ajax.readyState == 4){
             alert("image saved");
         }
}
    ajax.send(postData);
} 

当我在jquery中调用函数upload() ，什么也没有发生。 我收到弹出消息，指示图片已成功存储，但没有成功。

我想知道是否可能需要重写代码以适合更新的库？ 我觉得已经很老了？

谢谢！