Zend Form autosubmit problem after "onchange" event

<form id="uploadForm" enctype="multipart/form-data" method="post" action="http://example.com"><dl class="zend_form">
<dt id="image-label"><label for="image" class="required">Upload an image:</label></dt>
<dd>
<input type="hidden" name="MAX_FILE_SIZE" value="134217728" id="MAX_FILE_SIZE">
<input type="file" name="imageFile" id="image"></dd>
<dt id="submit-label"> </dt><dd id="submit-element">
<input type="submit" name="submit" id="submit" value="Завантажити"></dd></dl></form>

document.getElementById("imageFile").onchange = function() {
    document.getElementById("uploadForm").submit();
}