How to do a timer?

Need to make your own timer, just do not understand how to implement it. That is not clear to me how the numbers are divided by 2 parts 00, that is, to 0 0. Or somehow not a proper implementation?
https://jsfiddle.net/hollanditkzn/0qvwke7o/38/
June 7th 19 at 15:00
0 answer

Find more questions by tags JavaScriptjQuery