Add one hour to time

Question

I have two times as string a=10:00:00 and b=12:00:00

I need to subtract a from b and result should be 2. i.e. b-a=2

Again, I need to add 1 to a. i.e. a+1=11:00:00

Answer 1

Use moment.js, diff and add methods
https://code.sololearn.com/W0tCXropQZGO/?ref=app
https://code.sololearn.com/WZur4J60iKt5/?ref=app

Answer 2

Thank you Calviղ