javascriptajaxxmlhttprequest

XHR Upload Progress is 100% from the start

I'm trying out the new XMLHTTPRequestUpload feature to upload some files to a php script, it mostly works fine, the upload starts, I get the finish response etc - but the progress doesn't seem to work.

Looking that the event.loaded value - In firefox I seem to get a random value between 0 and the file size; in Chrome (where I'm mostly working) I get the total file size, even though the readystate hasn't reached '4' and the Developer Tools window still shows the file to be loading?

Any ideas?

Heres my code:

var xhr = new XMLHttpRequest()

xhr.upload.addEventListener('progress', function(event) {
    if (event.lengthComputable) {
        $('ajaxFeedbackDiv').innerHTML = event.loaded + ' / ' + event.total;
    }
}, false);

xhr.onreadystatechange = function(event) {
    if (event.target.readyState == 4) {
        updateFileList();
    }
};

xhr.open("POST", "_code/upload.php");
xhr.setRequestHeader("Cache-Control", "no-cache");
xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
xhr.setRequestHeader("X-File-Size", file.size);
xhr.setRequestHeader("X-File-Type", file.type);
xhr.setRequestHeader("Content-Type", "multipart/form-data");
xhr(file);

Many thanks

Ben

Solution

  • I also recently had some difficulty setting an event listener for XHR onprogress events. I ended up implementing it as an anonymous function, which works beautifully:

    xhr.upload.onprogress = function(evt)
{
    if (evt.lengthComputable)
    {
        var percentComplete = parseInt((evt.loaded / evt.total) * 100);
        console.log("Upload: " + percentComplete + "% complete")
    }
};

    I stumbled across a lot of other gotchas along the way, though, so it's quite likely one of those was tripping up my event listener. The only other difference between what you've got there and my setup is that I'm using xhr.sendAsBinary().