Add option to limit selected options in multiselect

[peteruhnak]

As addressed in issues #154 #463 #494 this adds option to limit number of selected options for multiselect.
$(select).chosen({ limit : 5 });

[Schyzophrenic]

Thank you for this. I am looking for the exact same feature. I hope it will be merged soon!

[n40i]

Yes, thank you - looking forward to seeing this in a build!

[dmarynych]

Great! Hope this feature will be in main build.

[billmn]

up!!

[pfiller]

I think using a big number is preferable to false as a default. Ideally, we'd use the actual length of the options for the limit as a default, but I think using something like 9999 is probably safe for all practical purposes. Using a default of 999 would eliminate part of the conditional.

[stof]

putting a number as default value would require changing the way the default is applied, as using || would forbid forcing false as value.

[pfiller]

Using false as a default complicates the logic when we test for it later. Using a number would allow one check: if @limit_choices >= @choices

[pfiller]

Thanks - just a few quibbles and we can get this merged in.

I think the name property should not be called limit, but rather something like limit_selected_options. We don't want any ambiguity with the name.

I also think that an event should be triggered if the limit is hit so that a message could possibly be displayed. Maybe something like liszt:maxselected?

I also made a comment where the default is set.

[peteruhnak]

I'll get into it. Speaking of ambiguity limit_selected_options sounds more like yes/no state so maybe max_selected_options?

[stof]

+1 for max_selected_options

[pfiller]

Yeah, that sounds great.

[pfiller]

Thanks a lot, @Polycode. It's really nice to close 3 issues with one PR.

I don't think this is perfect, but I think it'll help people who are careful with using it. It's pretty confusing to just have the results not show up with no explanation to the user, but the event gives a nice way to handle that situation.

[peteruhnak]

Thank you.

However I disagree about confusion - it's like having <input type="text" maxlength="...">. I feel that firing event once the limit is reached is too late, imo it's much better to have some kind of counter so user can immediately tell what's his current situation. Currently I can't think about any better usage of the liszt:maxselected than display dialog/alert with warning, but that is obtrusive. Or am I wrong?

[pfiller]

Though maxlength on an input is developer-friendly, it's not particularly user friendly. Stopping a user's intended behavior without explaining why isn't a wonderful experience. "Not perfect" does not mean it's bad, though -- I'm happy to have this merged in.

I agree that the event is probably coming too late for the user. Using Chosen's current behavior It is definitely possible to monitor the number of elements selected.

$("#some_field").val().length

This is a good something to build off of going forward. Thanks again @Polycode