A controlled input in React
React interview exercise on State, difficulty 1 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write NameForm with an `onSave(name)` prop: a controlled <input>, <small className="count">N characters</small>, and a submit <button> disabled while the trimmed name is empty. Submitting the form calls onSave with the trimmed name, prevents the browser's submit, and clears the input.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.