if (typeof dojo != 'undefined') {
    function eventRegister() {
	    var ziplookup = dojo.byId("ziplookupfield");
	    dojo.event.connect(ziplookup, "onkeyup", function(e) {
													    var ziplookup = dojo.byId("ziplookupfield");
													    ziplookup.value = ziplookup.value.replace(/[^0-9]/g, "");
													    if(ziplookup.value.length >= 5) {
														    //ziplookup.form.submit();
													    }
												    });
    }
    
    dojo.addOnLoad(eventRegister);
} else if (jQuery) {
    $(document).ready(function() {
        $("#ziplookupfield").keyup(function(e) {
            $(this).val($(this).val().replace(/[^0-9]/g, ""));
            if ($(this).val().length >= 5) {
                //this.form.submit();
            }
        });
    });
}