Untitled

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
	<title>Untitled</title>
	<script type="text/javascript">

		function limit_lines(str, limit)
		{
			var arr, i, len;
			
			str = str.replace(/\r/g, "");
			arr = str.split(/\n/g);
			len = arr.length;
			
			if ( len > limit )
			{
				str = "";
				for (i = 0; (i < len && str.split(/\n/g).length < limit); i++)
				        str += ((i > 0) ? "\n\r" : "") + arr[i];
			}
			
			return( str );
		}

	</script>
</head>

<body>

<textarea name="blah" cols="40" rows="12" onchange="if (this.value.split(/\n/g).length > 10) { alert('You have too many lines!'); this.value = limit_lines(this.value, 10); }"></textarea>

</body>
</html>