[abashev]

What

A Playground page at /playground/, after "Get started" in the navigation. Code goes on the left, the formatted result shows on the right, and the formatting runs in the browser. The formatter is compiled to WebAssembly by openjavaformat/open-java-format#196. The code is not sent anywhere, and the result is what the command line writes for the same input. Part of openjavaformat/open-java-format#21.

• Page: docs/playground/index.md. Every message is in the Markdown, links included, so the strict build checks them; the script only shows the one that applies.
• Thanks at the end of the page, to Denis Pavlyuchenko, who suggested the playground, and to cobr123, whose WebAssembly build it started from.
• Script and styles: docs/javascripts/playground.js and docs/stylesheets/playground.css, through extra_javascript and extra_css.
  • The script sets the page up through document$, because the site navigates without reloading. On other pages it does nothing.
  • It loads the module on this page only, once per visit. It starts it with GraalVM.run and learns from the promise whether loading failed.
  • Format runs on the button or Ctrl/⌘+Enter. Copy copies the result.
• Header tab: Playground is white on the theme's blue, like the Format button, on every page and in both palettes.
• Fetching the module: scripts/fetch-playground.sh takes the zip from the GitHub release that ojf_version names, checks it against that release's checksums_sha256.txt, and unpacks the two files next to the page. docs.yml runs it before the build, and so do mise run serve and mise run build. OJF_WASM_ZIP=<zip> takes a module built locally instead.

Before a release carries the module

21.0.1 has no zip. In that case the script writes a warning and the build carries on. The page then says that the playground comes with the next release and links to the command line. follow-releases.yml already redeploys the site when a new release is out, so the page starts working with no change here. A zip that is present but fails its checksum fails the build.

Tests

The tests ran with Playwright on a local build of the site, in Chromium 134, Firefox 135 and WebKit 18.4, against a module built from the formatter PR. All of these passed:

• Loading:
  • Other pages do not request the module.
  • The playground works both when reached through the navigation and when opened directly.
  • After leaving and coming back, it works again without downloading the module a second time.
• Formatting:
  • Format gives the same text as open-java-format-<version>-all.jar - for the starting example.
  • Pressing Format makes no request.
  • A warm format of the example takes 6 to 35 ms.
• Errors:
  • class B { gives a line:column error.
  • The shortcut works.
  • Formatting works again after the error is fixed.
• Layout:
  • Panes are side by side at 1400 px.
  • At 390 px in dark mode they are stacked, with no horizontal scroll.
• Fallback states:
  • With WebAssembly.validate returning false, the page shows the unsupported-browser message.
  • Without the module, the page shows "comes with the next release" and Format stays disabled.

zensical build --clean --strict passes with the module and without it. The fetch script was tried on all three paths: the real 21.0.1 release without the zip (a warning), a local zip, and a wrong checksum (fails).