For cross-tab communications, there are better APIs, like https://developer.mozilla.org/en-US/docs/Web/API/Broadcast_Channel_API https://developer.mozilla.org/e

For cross-tab communications, there are better APIs, like https://developer.mozilla.org/en-US/docs/Web/API/Broadcast_Channel_API https://developer.mozilla.org/en-US/docs/Web/API/Broadcast_C... For user-driven automations, something like Tampermonkey would be way better (and safer, since they can be domain-limited). I can think of no reason why a regular user would want to allow tabs to execute each other's code... that just seems like a setup for self-XSS attacks by people who don't know any better :( --------- edit: Sorry, re: the second part of your comment, I misunderstood what you meant. Like if you wanted to purposely script multiple identical tabs at the same time.