Get the target element which fired the event

Hi

I just started using the CKEditor(v 4.3.2) to edit web tempalte. I have button element populated through setData method. I am trying to find the clicked target but this is not working.

<form action="fileUpload.php">
    <input type="button" value="Upload File" id="fileBtn" name="fileBtn" />
</form>

CKEDITOR.instances['editor1'].on('contentDom', function() {
                    this.document.on('click', function(event){
                        //alert(event.sender == document.getElementById("fileBtn"));
                         alert(event.sender == 'fileBtn');
                     });
                });

Both of above alerts prints false. Is this correct way to get the sender element name?

I tried below way of getting, but that's not working -

var element = CKEDITOR.document.getById( 'fileBtn' );
element.on( 'click', function( ev ) {
        alert('fileBtn clicked');
    });

Thanks in advance.