How to build a c ountdown timer in Mongodb?

Hi All,

I’m building a to do app that has specific due dates. I want to build a timer into each task so that it counts down days, hours and minutes before its due. so for example:

Title: “Task A” - Due in: “2h: 32m: 24 sec”

What is the most cost efficient way to build this? I’m thinking triggers maybe? I’m new to MongoDB so any suggestions are appreciated.