Jsdom: document.activeElement is always null after upgrading to jsdom 15/16 (jest 25)

[eszthoff]

Basic info:

We use jest tests with expect(document.activeElement).toBe(myElement) pattern to determine if an element got correctly focused after an interaction. After upgrading to jest 25 (jsdom 15) all such tests broke, document.activeElement appears to be always null. It is also the case if we run it using jsDom 16.

Jest team advised me to open an issue here.

• Node.js version: 10.19.0
• jsdom version: 15 and 16
• jest version: 25.1.0

Minimal reproduction case

import * as React from 'react';

it('should find active element', () => {
    const wrapper = mount(<input />);
    const inputNode = wrapper.find('input').getDOMNode();
    expect(document.activeElement).not.toBe(inputNode);
    inputNode.focus();
    expect(document.activeElement).toBe(inputNode); // fails here with expected being null
});

How does similar code behave in browsers?

Focused element should be reflected in document.activeElement

[domenic]

This does not follow the issue template; it uses invalid JavaScript syntax, and references undefined functions.

Please edit the post to follow the issue template, producing a sample we can run in Node.js as a single file, and then add a comment. I would also strongly suggest a link to a jsbin or similar. At that time we can reopen and consider this issue.

[wojtekmaj]

Interestingly, without enzyme-related stuff it works just fine:

https://runkit.com/wojtekmaj/jsdom-15-2-16-document-activeelement-issue-ok

However, I think it might be tightly coupled with #2586 which is still a regression since v15.2:

https://runkit.com/wojtekmaj/jsdom-15-2-16-document-activeelement-issue

[felipeochoa]

Related: enzymejs/enzyme#2337

Looks like the break is caused by jsdom's increasing strictness about not setting activeElement to an element outside the document. The fix is on the client side, using the attachTo argument to the mount call.