Document limitations of JSDOM in Jest
Until https://gitlab.com/gitlab-org/gitlab-ce/issues/58205 is done, we are running Jest with JSDOM (which is the default). However JSDOM does not fully behave like a browser (https://github.com/jsdom/jsdom/issues/1322), for example scrollTo
or clientWidth
are missing (https://github.com/jsdom/jsdom/blob/423b837f5b6fe7f241b5b2932d150a6d7f3ef1e9/lib/jsdom/browser/Window.js#L595-L626). This is different from our Karma test suite which runs in headless Chrome, so we should document it in our frontend guide.