HTML behavior

Back to HTML/CSS.

<!doctype html>
<html>
  <head>
    <style>
      /* Valid content, but not a rendered browser stylesheet in this release. */
      body { margin: 0; }
    </style>
  </head>
  <body>
    <script>
      globalThis.behavior = {
        Start() {
          rustic.log("info", "web behavior started");
        },
        Update(dt) {},
        OnDestroy() {},
      };
    </script>
  </body>
</html>

Inline script bodies and linked <script src="..."> files are combined and evaluated as one sandboxed JavaScript behavior. The player resolves quoted src paths relative to the HTML document inside the play snapshot before the Web adapter extracts the script bodies. Absolute paths and any .. path component are rejected; remote script fetching is not implemented. Keep linked files in the same directory or a child directory of the HTML asset. A CSS-only asset has no callbacks and is therefore a valid no-op behavior. Module imports, DOM queries, events, fetches, storage, and layout APIs are not available.

Canonical callbacks are OnCreate, Start, FixedUpdate, Update, OnEnable, OnDisable, OnDestroy and OnStop; snake-case spellings remain compatible. Collision callbacks are not currently bound by the embedded Web/JavaScript adapter. Only methods actually present on globalThis.behavior run.

HTML layout and CSS styling for game UI are planned. The sample above exercises JavaScript callbacks only; it does not currently display a rendered HTML body.

A missing linked script is skipped with a runtime warning for that play session. Remaining linked and inline scripts continue running. Restore the file, stop Play, and start Play again to load it. Missing files are not retried during the session.