299476 - When calling a function via setTimeout() all parameters have to be passed

Status: RESOLVED DUPLICATE of bug 394769

(Core Graveyard :: Tracking, defect)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

This bug should be a tracking bug to fix all affected calls of setTimeout().

Calling a function without parameters over setTimeout() will work without any
issue. But don't try to call a function with at least one parameter in that way:

function f (event) 
{
  alert(typeof(event));
}

setTimeout(f, 100);

In that case RunTimeout doesn't pass an object to f(). Instead an "secret" final
argument that indicates timeout lateness is passed.

See: http://lxr.mozilla.org/seamonkey/source/dom/src/base/nsGlobalWindow.cpp#5248

To avoid such a failure, every function call over setTimeout() has to be
accomplished with the full list of function parameters. The correct way of the
above example would be: 

setTimeout(f, 100, null);

Comment 1

[Hixie (not reading bugmail)]

be: This would be a reason not to add lateness to HTML5... :-)

Comment 2

[Brendan Eich [:brendan]]

Indeed!

/be

Comment 3

[Boris Zbarsky [:bzbarsky]]

Not a DOM bug.  I presume this is supposed to track UI bugs caused by this or something?

Comment 4

[Henrik Skupin [:whimboo][⌚️UTC+2]]

(In reply to comment #3)
> Not a DOM bug.  I presume this is supposed to track UI bugs caused by this or
> something?

Correct. I have taken a short look at this issue by querying lxr but wasn't able to find another piece of code. There is already too much use of that function. ;) We have to wait and see.

Comment 5

[Reid]

I can confirm this on:

Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-GB; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11

Comment 6

[Paul Carduner]

Another side effect of this bug is that you can't call functions exposed via Flash's ExternalInterface from window.setTimeout, even if you pass all the parameters.  If your ExternalInterface function requires no parameters, window.setTimeout will still pass in the lateness value, which causes the flash plugin to throw this cryptic error message in your js console: "Error calling method on NPObject!" which will be thrown if the wrong number of arguments are passed (either too few or too many).

Comment 7

[Philipp von Weitershausen [:philikon]]

Given comment 1 and 2, wouldn't it make more sense to have our window.setTimeout implementation not add that lateness parameter, rather than fixing all of our own call sites? As comment 6 points out, our failure to meet be standard compliant causes real world bugs.

Comment 8

[:Gavin Sharp [email: [e-mail]]]

(In reply to Philipp von Weitershausen [:philikon] from comment #7)
> Given comment 1 and 2, wouldn't it make more sense to have our
> window.setTimeout implementation not add that lateness parameter, rather
> than fixing all of our own call sites?

Yes - that's bug 394769. I'm not sure what this bug is useful for now.