How to export images by using save as window?

Question

I have the following code. I need to convert canvas element in to image format and need to save. So i did the following in my script

exportImage: function (fileName, fileType) {
            var lnk = document.createElement('a'), e;
            lnk.download = fileName + "." + fileType;
            lnk.href = this.canvasElement.toDataURL("image/" + fileType).replace("image/" + fileType, "image/octet-stream");
            if (document.createEvent) {
                e = document.createEvent("MouseEvents");
                e.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
                lnk.dispatchEvent(e);
            }
            else if (lnk.fireEvent) {
                lnk.fireEvent("onclick");
            }
        },

But this code works fine in the firefox. But given file name is not set in chrome. And even save is not working in the IE.