In-browser image resize and upload

gistfile1.js

var createAndUploadThumbnailImg = function (fileObj) {    // i.e., <input type=file>
    console.log('making thumbnail for...');
    console.log(fileObj);

    var reader = new FileReader();
    reader.onload = function (e) {

        // create canvas obj (<canvas>, not added to DOM)
        // then give it a reference the URL (not on server; on page) made available by FileReader.readAsDataURL()
        // then use canvas to draw that image at smaller dimensions, effectively copying and resizing it
        //
        var canvas = document.createElement('canvas');
        var img = new Image();
        img.src = e.target.result;
        img.onload = function () {

            canvas.id = "myTempCanvas";
            canvas.width = 200; // TODO: calculate proper dimensions
            canvas.height = 200;

            if (canvas.getContext) {
                var cntxt = canvas.getContext("2d");
                cntxt.drawImage(img, 0, 0, canvas.width, canvas.height);
                var dataURL = canvas.toDataURL();

                if (dataURL != null && dataURL != undefined) {
                    $('#dacoverimg-thumb').attr('src', dataURL);
                    console.log("thumbnail img displayed");
                    console.log("... as base64...");
                    console.log(dataURL);

                    // The secret to getting a proper fileObj (Blob) with mime-type set
                    // is to xhr.get the thumbnail just created, resulting in a
                    // properly-constructed Blob object that can be POST'd using FormData
                    var xhr = new XMLHttpRequest();
                    xhr.addEventListener('progress', function(){
                        console.error('progress');
                        console.log(this);
                    });
                    xhr.open('GET', dataURL, true);
                    xhr.responseType = 'blob';
                    xhr.onload = function(e) {
                        console.log('grabbed thumbnail via URL...');
                        console.log(this);
                        
                        var formData = new FormData();
                        formData.append('file', this.response); // optional 3rd param: filename

                        $.ajax({
                            url: serverURL,
                            type: "POST",
                            data: formData,
                            processData: false,
                            contentType: false
                        })
                    };
                    xhr.send();

                }
                else {
                    alert('unable to get context');
                }
            }
        }
    };
    reader.readAsDataURL(fileObj);
};

only works in firefox as of Feb 28 2015...