Make Modal.enforceFocus easier to override/exempt

[zenorocha]

For many years, dozens of third-party libraries have been facing the same issue with Bootstrap's modal. The answer so far has been "override enforceFocus" #16050 #12216 #11686 #10610 #8537 #7371 #6996 #5114

That led to many apps adding this line to their code:

$.fn.modal.Constructor.prototype.enforceFocus = function() {};

Once they upgrade to Bootstrap 4, this line will no longer work. They will need to figure out that it changed to:

$.fn.modal.Constructor.prototype._enforceFocus = function() {};

Instead of asking people to monkey patch their projects, shouldn't this functionality be revisited and fixed? Maybe starting from #12142?

[whodabudda]

Oy!! Days of trolling through code and finally stumbled on this! Thank you so much for the post. What a difference a character makes. It would be nice if 3rd party vendors kept the old interface and aliased it to the new, at least for a few releases as deprecated. I was ready to toss out bootstrap modals altogether.

[Johann-S]

With focus option to false, enforceFocus isn't called see : http://v4-alpha.getbootstrap.com/components/modal/#options + https://github.com/twbs/bootstrap/blob/v4-dev/js/src/modal.js#L251

[guilhermecfviana]

Thank you very much @zenorocha !!!