<script src="http://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
<script src="http://malsup.github.com/jquery.form.js"></script>
<script>
$(document).ready(function() {
$('input[type="checkbox"]:checked').parent().each(function(){
$(this).ajaxForm(function() {
alert('some');});});
$('#myButton').click(function() {
$("input[type='checkbox']:checked" ).each(function(){
$(this).ajaxSubmit();
alert('q'); });
return false;  }); });
</script>
<form id="form1" method="post">
<input type="text" id="name1" name="value" value="">
<input type="checkbox" id="cek">
<input type="submit"  class="update_form"  value="Save Changes"> <!-- changed -->
</form>

<form id="form2" method="post">
<input type="text" id="name2" name="value" value="">
<input type="checkbox" id="cek">
<input type="submit"  class="update_form"  value="Save Changes"> <!-- changed -->
</form>

<form id="form3" method="post">
<input type="text" id="name2" name="value" value="">
<input type="checkbox" id="cek">
<input type="submit"  class="update_form"  value="Save Changes"> <!-- changed -->
</form>
<input type="button" id="myButton"/>