Promissa guides you through Await Station. Standing in the way: Race Condition Rex — every mistake this lane teaches you to avoid. Promises, async/await, fetch, storage and the window — talk to servers without freezing the page.
All 26 lessons below are free, need no signup, and each one opens as a comic issue with a live try-it sandbox, a task list that pays XP, and a narrator that reads it aloud. Progress is stored in your own browser — nothing is uploaded anywhere.