What to work through
Work through a rich text editor as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Format text: bold, italic, links, headings and lists
- Paste content copied from other apps and web pages, keeping the formatting the editor supports
- Undo and redo every change, formatting and pastes included
- Save what was written and open it again exactly as it was
- Accept typing in any language, input methods for scripts such as Japanese included
Constraints to discuss
- A keystroke shows in the same frame, the editor's own work under 10 milliseconds
- A click on a toolbar button answers within 200 milliseconds
- Pasted content never runs a script or carries unsafe markup into the page
- Spell check, screen readers and touch keep working inside the editor
Need a starting point?
Watch for these common gaps as you prepare:
- Treating the document as one big string
- Relying on the editable area alone, with the browser's own formatting commands and undo
- Pasting HTML without cleaning it, or cleaning it after it is in the page
- Redrawing the editor on each keystroke, so the cursor jumps and input methods break
- Naming an editor library as the whole answer instead of a building block
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.