HTML/Javascript - limiting characters in a textarea

Here is a way to limit the amount of text entered into a textarea. Note, this works in both IE and FireFox. Also, this only limits characters entered via keystrokes and does not work for copy/paste.

/* -------------------------------------------------------------------------
limits the amount of text that can be typed into a textarea
example usage: <textarea onkeypress="return limitText(event, this, 40);">
--------------------------------------------------------------------------*/
limitText : function(event, textArea, maxChars) {
var result = true;

if (textArea.value.length >= maxChars) {

if (textArea.createTextRange) {
var range = document.selection.createRange().duplicate();
result = range.text.length > 0;
} else {
result = event.keyCode in { // always let these keys through
37 : "left",
39 : "right",
38 : "up",
40 : "down",
33 : "pageUp",
34 : "pageDown",
46 : "del",
36 : "home",
35 : "end",
27 : "esc",
8 : "back"
};
}
}

return result
} // limitText()