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Encrypted Media Extensions (EME) is the web platform’s standard way to enable playback of encrypted, DRM-protected media in the browser. Rather than handling decryption directly, your application coordinates with the browser’s Content Decryption Module (CDM): it requests access to a media key system via Navigator.requestMediaKeySystemAccess(), attaches the resulting MediaKeys to a specific HTMLMediaElement with setMediaKeys(), and then manages the message exchange for licenses/keys through a MediaKeySession. When the media element encounters encrypted initialization data, it fires an encrypted event (represented by MediaEncryptedEvent), and the CDM can emit session messages (MediaKeyMessageEvent) that your app relays to whatever key infrastructure you use. EME is widely available across modern browsers and is typically restricted to secure contexts (HTTPS).

The experimental EditContext API gives developers a new foundation for building custom rich text editors by separating text input and selection from rendering. Instead of relying on contenteditable, you attach an EditContext to a focusable element and manage your own text model, selection state, and UI updates—while still receiving browser-grade events for typing, caret movement, and IME composition. This demo highlights the core event flow and why character bounds matter for accurate input UI, especially in custom-rendered editors.