On Apr 6, 2006, at 6:50 PM, Ian Hickson wrote:
On Thu, 6 Apr 2006, Maciej Stachowiak wrote:
Is there any reason this would be better than (Plan B):
B. Window contains inelegant ECMAScript-specific Timer API for
compatibility
but also adds new elegant and language-neutral Timer API.
Please, please don't add a new timer API to JavaScript.
That would be Plan C, then. Robin's proposal was to add a new timer
API, including to JavaScript, but as a separate spec.
I would like to note that if we don't add a timer API that works
across languages, the SVG WG almost certainly will, and that
effectively means all browsers that support SVG have to implement it
on every global object anyway. (Or rather, we'll have a much harder
time convincing them to remove it.) So realistically the only
question at hand is "who defines it and in what spec".
I think the biggest problem with the JS timer API is the numeric IDs
that you get back from the set functions and pass to the cancel
functions. You can't just pass the number as a timer ID to other code
that may wish to cancel the timer. You need to know the window object
that started the timer and whether it was a Timeout or an Interval.
So it's not obvious what to use for a sane concept of timer ID. I
would guess existing code that cares stores just the number, which
means it could break in a CDF situation and requires implicit
knowledge in cancel code of what kind of timer it was.
Less severe issues with current API:
- You can't change the interval of a running timer.
- You can't have different initial and repeat intervals.
- Timer callback doesn't get the Timer as an argument, so if you want
to make, say, a repeating timer that stops itself after some number
of repeats, you have to store global state out of band to let it find
its own timer ID.
- You can't check how much time is left on a timer (sometimes
interesting for some uses).
So adding a better API would have actual benefits for JavaScript
developers and not just be a gratuitous duplication.
I would also add that it's entirely possible to define a Timer API
that solves these issues, but nontheless is implementable as JS
library code, in case anyone wants to use it in UAs that don't
support it directly. (Yes, third-party JS libraries could just
provide that - no, I don't think that's a reason not to do it.)
Regards,
Maciej
