Here is the code to automatically select options from selectElementA. After each change in selectElementA, an ajax is done and loads new options in selectElementB then I read this new values by the Read_Data function. The problem is that the change event after making a change in selectElementA is not fired.
--------------------------------------------------------------------------------------------------------------
var selectElementA=$('#ctl00_pageContentRegion_frameManufacturer');
var selectElementB=$('#frameModel');
var options = selectElementA.options;
for (var j=0; j< options.length;j++) {
jQuery(selectElementA).find("option")[j].selected = true;
setTimeout(function(){jQuery(selectElementA).trigger("change");},5000);
$(document).ajaxComplete(function complete(e){
Read_Data(selectElementB);
$(document).unbind('ajaxComplete',complete);
}).trigger('ajaxComplete');
}