My idea is to use data from multiple rows to run computations in javascript.

Example here would be multiple rows for a timecard are for the same day of work:

You can see both rows are for 9/6/2019.

Row 2 however starts before their first shift ended.  So this overlap needs to be flagged.

Likewise I want to build in logic to look at total time between the days to know that a break should have also been taken.

Is there any way to easily group data where all rows match Date column, and then run calculations from there?