In the following script, when del key is pressed it returns 46 instead of 127, which is the ASCII code of del key.
function countLength(evt) {
var inp = (evt.which) ? evt.which : event.keyCode;
alert (inp);
return true;
}
Values returned by event.keyCode are not ASCII codes. They just indicate which key was pressed on the keyboard. For example pressing 0-key on the topmost row of the keyboard returns 48, but pressing 0 on numberblock returns 96.
To convert keycodes to ASCII , you have to use some kind of an array containing corresponding values. In this task you have to check all other keys pressed simultaneously, like shiftKey and altKey to have correct results.
keypress event, and when using that, you don't have to mess around with checking modifier keys such as Shift or Alt.
keypress you can't have all keys pressed (delete for example). I was just about to add this issue to my answer, but it seems to be unnecessary, beacause it is in your comment already.keypress detects everything printable, but it's true that it doesn't fire for non-printable keystrokes in all browsers. For detecting the Delete key I'd use keydown.I am not sure where you are getting evt from becaue it is standalone function. If you are passing it then change:
event.keyCode;
To:
evt.keyCode;
Or try changing evt in all three cases to event or vice versa.
<form name="formA" id="formA" action="#" > <textarea id="txt" name="txt" onkeydown="return countLength(event)"></textarea> </form>
event to evt in all places and opposite of it for all again if it does not work.