window.setInterval and window.setTimeout have a [timeout] argument which does not work

[ShubhamVG]

The function declaration of both window.setInterval and window.setTimeout look the same i.e.,

  external int setInterval(
    TimerHandler handler,
    JSAny? arguments, [
    int timeout,
  ]);

And according to MDN, the JS declaration is

setInterval(func, delay, arg1, arg2, /* …, */ argN)

At first, I thought that timeout is the delay parameter but it wasn't. Setting timeout did not affect the delay at all.
After that, I thought that maybe timeout is the time after which the interval closes/clears itself. That does not turn out to be the case either.

So far, setting timeout seems to be NOT do anything and I could not find any JS equivalent feature either.

So, that's why I have this question: What does the [timeout] argument do?

[ykmnkmi]

I think the timeout should be the second argument, and the rest should be the other arguments.

import 'dart:js_interop';

import 'package:web/web.dart';

void main() {
  JSExportedDartFunction jsHandler = onEvent.toJS;
  window.setInterval(jsHandler, /* timeout */ 1000.toJS, /* args */ 1);
}

void onEvent(/* args */ int value) {
  log(value.toJS); // 1
}

@JS('console.log')
external void log(JSAny message);

[ykmnkmi]

Use this (remove args if you don't need them)

extension on Window {
  @JS('setInterval')
  external int setInterval$(
    TimerHandler handler,
    int timeout, [
    JSAny? args,
  ]);
}

[srujzs]

https://github.com/w3c/webref/blob/6e9c0167c76cd5aaaf01b51669639bb7e916d52b/ed/idl/html.idl#L2300

It looks like we're not treating variadic arguments as optional. Because we believe optional parameters should always go after required ones, the ordering gets flipped:

web/web_generator/lib/src/translator.dart

Line 1033 in c2d5f63

return _overridableMember<code.Method>(

.

I believe the fix should just be to consider variadic arguments as optional. It looks like that is the intention of the spec:

An argument is considered to be an optional argument if it is declared with the optional keyword. The final argument of a variadic operation is also considered to be an optional argument.

Olzhas is correct here wrt a workaround.