ใช้ Javascript ตรวจสอบการขึ้นบรรทัดใหม่ใน textarea ได้ยังไงครับ

<script src="http://code.jquery.com/jquery-latest.js"></script>
<textarea id="myArea"></textarea><br />
คุณกด Enter จำนวน <input type="text" id="keycount" /> ครั้ง

<script>
var keyCount = 0;
$("textarea#myArea").keyup(function (event) {
  var keyCode = event.keyCode || event.which;

  if (keyCode == 13) {
    keyCount++;    
    $("#keycount").val(keyCount);
  }
});
</script>

<script src="http://code.jquery.com/jquery-latest.js"></script>
<form method="post" >
<textarea id="myArea"></textarea><br />

<input type="submit" value="Saving changed ....." />
</form>
<script>
$("form").submit(function(){
    var allText = $("textarea#myArea").text();
    allText.replace(/\r\n/g, "<br />");
    $("textarea#myArea").text(allText);
});
</script>

 <script src="http://code.jquery.com/jquery-latest.js"></script>
<form method="post" >
<textarea id="myArea"></textarea><br />

<input type="submit" value="Saving changed ....." />
</form>

<div>
</div>

<script>
$("form").submit(function(event){
	event.preventDefault();
    var allText = $("textarea#myArea").text();
   allText = "<pre>"+allText+"</pre>";
    $("div").html(allText);
});
</script>

<textarea id="myArea" name="myArea"></textarea><br />
<input type="button"  id="saveChange" value="Saving changed ....." />

<div>
</div>

<script type="text/javascript">
$("input#saveChange").click(function(event){
	var allText =  $("textarea#myArea").text().replace(/\n/g, "<br />");
	$("div").html(allText);
});
</script>