Is there a way to use this to forcibly eliminate javascript execution on some pages? If you ran a shadow dom, or background tab of some maliscious site, and for

Is there a way to use this to forcibly eliminate javascript execution on some pages? If you ran a shadow dom, or background tab of some maliscious site, and forced an alert() on the page, could you then (in another context tab) run the page. It wouldn't make a lot of sense in practicality, but would be interesting to use alert() to block js execution, or even some of these olders legacy feature sets.