สอบถามเรื่องการเช็คค่า ใน textBox ให้กิด event โดยที่ไม่มีปุ่ม submit

<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<input type="text" id="test" name="test" maxlength="12">
<script type="text/javascript">
$(function(){
$("#test").keyup(function(){
	var txt = $(this).val();
	if(txt.length == 12){
		alert(txt);
		//do some thing
		//$.post();
	}
});
});
</script>

<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>

<input type="text" id="test" name="test" maxlength="12">

<script type="text/javascript">
$(function(){
$("#test").keyup(function(){
	var txt = $(this).val();
	if(txt.length == 12){
		alert(txt);
		//do some thing
		//$.post();
		$.post( "test_ans.php", $( "#test" ).serialize() );
	}
});
});
</script>

<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<input type="text" id="test" name="test" maxlength="12">
<div id="callBack"></div>
<script type="text/javascript">
$(function(){
$("#test").keyup(function(){
	var txt = $(this).val();
	if(txt.length == 12){
		alert(txt);
		//do some thing
		$.post('test_ans.php',{'data':txt},function(data){
			$("#callBack").html(data);
		});
	}
});
});
</script>

<?PHP
echo $_POST['data'];
?>

<form id='frm_test'>
<input type="text" id="test1" name="test1" maxlength="12">
<input type="text" id="test2" name="test2" maxlength="12">
<input type="text" id="test3" name="test3" maxlength="12">
<input type="text" id="test4" name="test4" maxlength="12">
</form>

$.post("test_ans.php",$("#frm_test").serialize(),function(data){
//do some thing
});

var test1 = $("#test1").val();
var test4 = $("#test4").val();
$.post("test_ans.php",{'test1':test1,'test4':test4},function(data){
//do some thing
});