Playwright

Playwright drives a real browser through a static site the way readers use it, which makes it the tool for the parts of a static site that can break without the HTML changing: search and its index files, menus and focus handling, version switchers, forms backed by functions. The guides below use it in three places — on every pull request, against preview deploys, and on a schedule against production.

Two guides go beyond pass or fail. One measures layout shift and interaction latency inside existing tests, catching the regressions Lighthouse cannot see because it never clicks or scrolls. Another works through the causes of flaky runs against previews — the wrong deploy, cold caches, timing assumptions and third-party scripts — because a suite that fails one run in six stops being trusted.