useState 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 Counter with props `initial` (default 0) and `step` (default 1): <button className="dec">, <output>, <button className="inc"> and <button className="reset">. The buttons move the value by step and reset returns to initial; the value never goes below 0, and dec is disabled at 0.
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.