[DHTML] Form Field Limiter

[DimX]

One thing annoys me though: the onkeyup event is used, so when the maximum length gets exceeded, the last (disallowed) character still shows up for a moment.
And when I keep the key pressed, the character keeps being added to the field until the key is released, then the field gets trimed.

[mburt]

That's why, in my example I used onkeydown().

[Twey]

That's why, in my example I used onkeydown().

But then if you hold the key down, it never gets trimmed. The only way to make sure it's always updated is to use setInterval() to check regularly, but this is terribly inefficient.

[DimX]

But then if you hold the key down, it never gets trimmed.

Why so? The keydown/keypress events keep firing continuously while the key is pressed.

Edit:
A simplest example that works:

<input type="text" onkeypress="return this.value.length < 5" />

Edit:
Whoops, okay, this example isn't perfect (you can't delete text when field is full), but the onkeypress event still works as expected.

[mburt]

Just call the function initially using window.onload or equivalent. Then it will have the desired effect.

[Twey]

Why so? The keydown/keypress events keep firing continuously while the key is pressed.

keypress does, keydown doesn't. Also, keypress still suffers from the validation problem: it's only called after the new data is entered. The inability to delete or navigate through text when the field is full is another problem with returning false. If we combine keypress and keyup, we can lessen the appearance of the extra characters (sample updated), but one still appears due to keypress validating before the effect.

[DimX]

keypress does, keydown doesn't.

Hmm, in IE and Firefox keydown also does, in Opera not.

Also, keypress still suffers from the validation problem: it's only called after the new data is entered.

It's not, it's called before the new data is inserted.

[Twey]

Er, yes, sorry. Thought one thing and typed another.

Hmm, in IE and Firefox keydown also does, in Opera not.

In Konqueror it doesn't either.

[djr33]

Works great, but pasting (with CTRL+V and similar methods, probably) gets around it.

[Twey]

Not ctrl-V, but right-clicking and clicking "paste" would. That's not really an issue though, it's not meant to be a secure solution (we'd be in some trouble if it were The only thing it needs to do is provide some indication to the user when they've gone over the limit and it's pointless to type any more.