Changed event triggered when using data-max-options?

[alexcrooks]

I've been working with bootstrap-select recently, in particular with dropdown menus using the data-max-options option, and how it triggers the changed.bs.select event.

So say we have a dropdown as such, with data-max-options="2"

| 2 selected |
| Opt 1 √    |
| Opt 2 √    |
| Opt 3      |

When we select Opt 3, the dropdown changes to look like

| 2 selected |
| Opt 1 √    |
| Opt 2      |
| Opt 3 √    |

Currently one event is fired: changed.bs.select for Opt 3 added.

In my opinion, two events should be fired: changed.bs.select for Opt 2 removed, and then changed.bs.select for Opt 3 added.

I'm happy to submit a PR for this if you think it is a valid bug, just wanted to hear your thoughts before writing the code.

[caseyjhol]

Hrmmm...that isn't normal functionality for that feature. If maxOptions is set to 2, and you have 2 options already selected, selecting a 3rd option should show a notification that the limit is 2, and the third option won't be selected. There is a bug there, however. Since the 3rd option is never technically selected, the changed.bs.select event shouldn't even be fired.

[alexcrooks]

I'm not sure if I agree. Say I have a native dropdown as such:

<select>
  <option selected>Foo</option>
  <option>Bar</option>
  <option>Baz</option>
</select>

When I select "Bar", it becomes selected -- there aren't any implementations of <select> that show a notification, they all change the selected attribute to the newly-selected option. A native <select> is functionally equivalent to <select class="selectpicker" data-max-options="1">, so I think it makes sense that the two share the same UX.

If you're not showing a notification, though, then what is the logic for which option you unselect? Oldest-gets-dropped?

With a native dropdown, when you select an option, the previously selected option becomes unselected, but it only fires a single changed event. So maybe this whole issue is moot? My current use-case for bootstrap-select needs to know what's unselected but it's sounding like I should be keeping track of that state in my implementation instead.

[caseyjhol]

If you're using maxOptions, and you've reached your limit, a notification alerts the user - otherwise it would be too confusing to change the user's selection. We could maybe show a notification prior to attempting to select the extra option, but that's a different topic.