IconVault's EditContext playground wires a working custom text editor to the real `EditContext` API: type with your physical keyboard, open an IME or the emoji picker to fire genuine composition events, and watch every textupdate, characterboundsupdate and composition event land in the log with its exact payload. It is free and runs fully in your browser.

You will learn the core idea (the browser routes text input to your model instead of mutating your DOM), the event protocol for applying remote edits, why character bounds matter for IME candidate windows, and the keyboard handling a real canvas editor still owns itself. Where EditContext is missing, the tool says so instead of pretending.