JS function - calculate data by months / weeks. URGENTLY

THE ORDER IS URGENT.
You need to start today) Ideally finish by tomorrow morning.

Brief description:
- There are resources (people)
- There is their loading, which comes in the form of an array of ranges with start date - end date

It is necessary to calculate their load in hours or percentages (taking into account input data like an 8-hour working day and accounting / not counting weekends).

Special optimization is not required - the main result.