the second parameter of toggleClass() should be allowed to be non-boolean

[waltertross]

var modif = $('#x').hasClass('xModif') OR $('#y').find('.yModif').length;

$('#z).toggleClass('zModif', modif);

(please replace the OR with a double vertical bar, which the tracking system refuses to display)

This example doesn't work currently, unless one replaces length with length > 0, because modif will be true if hasClass() returns true, but it will be an integer otherwise, and toggleClass() currently only uses the second parameter if it is of boolean type.

This example is particularly tricky, because many people tend to think that the OR condition always produces a boolean, and because it will not fail in all cases.

The suggested enhancement is to ignore the second parameter of toggleClass() only if it is undefined, converting it to boolean otherwise.

Alternatively, a big warning in the documentation is suggested.

[dmethvin]

I've been bitten by this before as well so now it's burned into my memory. Given the current signature of .toggleClass() it seems like it would be possible to treat the switch arg as truthy/falsy as long as it is not undefined, or check for arguments.length>1.

[scottgonzalez]

Allowing non-booleans would break jQuery UI's .toggleClass() implementation which allows animating between two classes.

[waltertross]

I hadn't noticed toggleClass() in the UI because I'm new to jQuery. In my eyes, this is a small case of bad design.

A warning in the documentation, maybe exceptionally mentioning the UI, seems to be the only viable solution.

[SlexAxton]

+1 for stronger docs on this. Agree that changing it would break too much potential stuff.

ccing docs team for updates.