use-isInstance ============== Prefer ``.isInstance()`` in chrome scripts over the standard ``instanceof`` operator for DOM interfaces, since the latter will return false when the object is created from a different context. These files are covered: - ``*.sys.mjs`` - ``*.jsm`` - ``*.jsm.js`` - ``*.xhtml`` with ``there.is.only.xul`` - ``*.js`` with a heuristic Since there is no straightforward way to detect chrome scripts, currently the linter assumes that any script including the following words are chrome privileged. This of course may not be sufficient and is open for change: - ``ChromeUtils``, but not ``SpecialPowers.ChromeUtils`` - ``BrowserTestUtils``, ``PlacesUtils`` - ``document.createXULElement`` - ``loader.lazyRequireGetter`` - ``Services.foo``, but not ``SpecialPowers.Services.foo`` Examples of incorrect code for this rule: ----------------------------------------- .. code-block:: js node instanceof Node text instanceof win.Text target instanceof this.contentWindow.HTMLAudioElement Examples of correct code for this rule: --------------------------------------- .. code-block:: js Node.isInstance(node) win.Text.isInstance(text) this.contentWindow.HTMLAudioElement.isInstance(target)