Below is the code I am using which basically passes multiple files to be uploaded. In the loop each file is resized client side and then uploaded.

I want to execute an ajax call after the loop is finished uploading the photos. The ajax call basically reloads a specific div and refreshes the photos.

How do I prevent the ajax call from executing until the loop has finished.

```
if (window.File && window.FileReader && window.FileList && window.Blob)
    {       
        var files = document.getElementById('filesToUpload').files;    
        for(var i = 0; i < files.length; i++) 
        {
            resizeAndUpload(files[i]);

        }

        // when loop finished, execute ajax call
            $.ajax
            ({
                type: "POST",
                url: "photos.php",
                data: dataString,
                success: function(html)
                {
                    $("#photo-body").html(html);
                }       
            });
        }       
    }

function resizeAndUpload(file)
{
    var reader = new FileReader();
    reader.onloadend = function() 
    {
        var tempImg = new Image();
        tempImg.src = reader.result;
        tempImg.onload = function()
        {
            var MAX_WIDTH = 382.25;
            var MAX_HEIGHT = 258.5;
            var tempW = tempImg.width;
            var tempH = tempImg.height;

            if (tempW > tempH) 
            {
                if (tempW > MAX_WIDTH)
                {
                    tempH *= MAX_WIDTH / tempW;
                    tempW = MAX_WIDTH;
                }
            } 
            else
            {
                if (tempH > MAX_HEIGHT)
                {
                    tempW *= MAX_HEIGHT / tempH;
                    tempH = MAX_HEIGHT;
                }
            }

            var canvas = document.createElement('canvas');
            canvas.width = tempW;
            canvas.height = tempH;
            var ctx = canvas.getContext("2d");
            ctx.drawImage(this, 0, 0, tempW, tempH);
            var dataURL = canvas.toDataURL("image/jpeg");

            var xhr = new XMLHttpRequest();
            xhr.onreadystatechange = function(ev)
            {
                document.getElementById('filesInfo').innerHTML = 'Upload Complete';

            };
            xhr.open('POST', 'upload-resized-photos.php', true);
            xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
            var data = 'image=' + dataURL;
            xhr.send(data); 

        }
    }
    reader.readAsDataURL(file);
}

var _validFileExtensions = [".jpg", ".jpeg", ".bmp", ".gif", ".png"];    
function Validate(oForm)
{
    var arrInputs = oForm.getElementsByTagName("input");
    for (var i = 0; i < arrInputs.length; i++) 
    {
        var oInput = arrInputs[i];
        if (oInput.type == "file")
        {
            var sFileName = oInput.value;
            if (sFileName.length > 0)
            {
                var blnValid = false;
                for (var j = 0; j < _validFileExtensions.length; j++) 
                {
                    var sCurExtension = _validFileExtensions[j];
                    if (sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length).toLowerCase() == sCurExtension.toLowerCase()) 
                    {
                        blnValid = true;
                        break;
                    }
                }

                if (!blnValid) 
                {
                    alert("Sorry, " + sFileName + " is invalid, allowed extensions are: " + _validFileExtensions.join(", "));
                    return false;
                }   
            }
        }
    }
    return true;
}

```