javascript - A click to start the countdown timer and a second one to Pause the timer in the same button - Stack Overflow
JavaScript Timer with Start/Pause/Stop Button | Naveen Bhardwaj
Creating a countdown timer RxJS vs Vanilla JS - DEV Community
GitHub - TheBestCoders/Javascript-Timer: Javascript Timer with the feature to keep running even if page refresh or browser close, also have start, pause, reset features.