countdown-timer-with-a-flip-animation JS

it was fun and easy until animating the card comes to play...but the result worth it .. to create the flip animation...the flip animation basically have a callback function which receive two parameters(arguments)..flipcard[the element that we want to display] and the time that we calculated[newnumber] .. i also consider formatting the time when the number is single digit so i add 0 when its single digit.. another thing to consider is when the countdown ends the page should display some kind of message... it helps me to practice adding animation event listener when it start and when it ends and finally JS will do the rest of magic starting from dynamically adding the exact time when will end the countdown...if u have a better procedure please leave a comment