Checking file size during upload and stopping upload exceeding file size limit with javascript?

Question

Is there a way to use javascript or jquery to check the progress of a file upload (ie how many bytes or kb the server has received) and to cut off the upload if it exceeds a certain limit, showing the user a warning/error message? Thank you.

Answer 1

This example might help you out: http://js1.hotblocks.nl/tests/ajax/file-drag-drop.html

(It also includes the drag/drop interface but that's easily ignored.)

Basically what it comes down to is this:

<input id=files type=file>

<script>
document.getElementById('files').addEventListener('change', function(e) {
    var file = this.files[0];
    var xhr = new XMLHttpRequest();
    xhr.file = file; // not necessary if you create scopes like this
    xhr.addEventListener('progress', function(e) {
        var done = e.position || e.loaded, total = e.totalSize || e.total;
        console.log('xhr progress: ' + (Math.floor(done/total*1000)/10) + '%');
    }, false);
    if ( xhr.upload ) {
        xhr.upload.onprogress = function(e) {
            var done = e.position || e.loaded, total = e.totalSize || e.total;
            console.log('xhr.upload progress: ' + done + ' / ' + total + ' = ' + (Math.floor(done/total*1000)/10) + '%');
        };
    }
    xhr.onreadystatechange = function(e) {
        if ( 4 == this.readyState ) {
            console.log(['xhr upload complete', e]);
        }
    };
    xhr.open('post', url, true);
    xhr.send(file);
}, false);
</script>

In the progress method you got the file size etc. I hope this solves your issue. Regards.