A modal through a portal in React
React interview exercise on Patterns, difficulty 2 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 Modal({ open, container, onClose, children }): nothing when closed; when open, a portal into `container` with <div className="backdrop"> around <div className="dialog" role="dialog"> holding the children. Clicking the backdrop (not the dialog) and pressing Escape anywhere in the dialog call onClose.
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.