Fundamentals of Rich Text Editors

Rich text editors (WYSIWYG) are deceptively complex. The browser's contenteditable API is too permissive and inconsistent to build on directly, so modern editors like Tiptap, ProseMirror, and Lexical all share the same foundational architecture: a document model as the source of truth (not the DOM), a semantic selection model, transactions for all state changes, and a rendering layer that computes minimal DOM diffs. The post explains each layer in depth, covering schema rules, custom atomic inline nodes (e.g., Slack-style mentions), serialization formats (JSON, HTML, Markdown), and why editors should be treated as self-contained state machines rather than controlled React components. Performance best practices and common pitfalls are also addressed.