Reference material for task1
https://github.com/devression/Todo-List-App
Reference material for task2
https://www.javascripttutorial.net/javascript-dom/javascript-countdown-timer/
Reference material for task3
https://www.youtube.com/watch?v=OPnPqc9YWSA
Reference material for task4
https://www.youtube.com/watch?v=9GqhvxHNFag&list=PLOfzxGau1V5XoFTrzwmdb3uhUtn8nJDNE&index=8