Intersecting time slots

Question

I am working on a booking system which works around the user selecting a time slot and I am stuck attempting to check for overlapping bookings.

I am attempting to create a function which returns all the available time slots. I have an array called bookings which are the bookings for that day, and I have an array called slots.

I have tried looping through the arrays and attempting this:

if (slot.start > booking.dateStart.clone().addMinutes(-30) && slot.end < booking.dateEnd.clone().addMinutes(30))

To check for any overlap, and if there is I splice the slot from the array. I need to leave a 30 minute gap between each booking so that is why I am adding minutes.