Let’s consider this example, where HTML page has a TEXTAREA and an INBOX.  When user types inside TextArea, Inbox should show the length of TextArea string.

<script type="text/javascript"> 
 function TTLength(objTT){ 
 var tt= document.getElementById('TXT1'); 
 tt.value = objTT.value.length; 
 } 
</script> 
<textarea onKeyDown="TTLength(this);" onKeyUp="TTLength(this);" rows="10"> 
 This Text Area Contains a string With Newline Characters 
</textarea>
 <input type="text" id="TXT1" value="TT Length"/>

Let’s see how this page behaves in IE8 and in Firefox 3.6.11.

IE8	Firefox

As you can see that IE and FF return two different values for the length of an identical  string in TextArea and that could be a serious problem, if you are trying to validate the string length before updating the database.

It appears that IE counts all characters in a string, and Firefox ignores newline characters.  That explains the difference in the result.  Now, how do we fix that?

My only solution at this point is to add a server-side validation in addition to JavaScript to prevent ugly SQL errors on update.