[added] support Array, HTMLCollection and NodeList values for appElement

[eemeli]

Changes proposed:

• Hide multiple app elements, not just one
• Accept Array, HTMLCollection & NodeList values for the appElement prop

While working with an application that uses more than one top-level element, it became obvious that providing a fully accessible experience via react-modal is challenging, as it's currently only able to hide one app element.

The fix for this is pretty simple, and should have no effect on existing users. The accepted shape of the appElement value now also includes Array, HTMLCollection (returned by document.getElementsBy*) and NodeList (returned by document.querySelectorAll).

As a result of this change, it becomes easier to use react-modal to provide a fully accessible experience.

Acceptance Checklist:

• The commit message follows the guidelines in CONTRIBUTING.md.
• Documentation (README.md) and examples have been updated as needed.
• If this is a code change, a spec testing the functionality has been added.
• If the commit message has [changed] or [removed], there is an upgrade path above.

[coveralls]

Coverage increased (+0.2%) to 82.857% when pulling 3e950cd on eemeli:multi-root into c9d8e2d on reactjs:master.

[diasbruno]

Looks great. Bom trabalho!

Modal.setAppElement()...I'm worried this can potentially hold dead elements.

Any thoughts?

[eemeli]

Modal.setAppElement()...I'm worried this can potentially hold dead elements.

That is a possibility. Proactively getting rid of dead elements would probably require adding something like a document.body.contains(...) check within the validateElement() call to act as a filter. It would be nice if a WeakSet could be used, but that's not iterable.

Should I add that sort of filter?

[diasbruno]

It would be nice if a WeakSet

Yeah, totally agree.

I don't know if we should be defensive in this case, or, just write it in the docs warning about it.

[diasbruno]

Thanks, @eemeli.

[eemeli]

Any chance of getting a release including this sometime soon? 😇

[diasbruno]

Sorry for taking soooo long...released version 3.13.1.