Javascript subtract time spans from each other

Question

Suppose I have a time span {"start_time":"8:30", "end_time":"18:00"}

I want to subtract other time span like {"start_time":"12:30", "end_time":"14:00"} and get a result of:
[{"start_time":"8:30", "end_time":"12:30"},{"start_time":"14:00", "end_time":"18:00"}]

EDIT: I will also require to subtract other time spans next eg [{"start_time":"8:30", "end_time":"12:30"},{"start_time":"14:00", "end_time":"18:00"}] - {"start_time":"16:30", "end_time":"17:00"} which should give me [{"start_time":"8:30", "end_time":"12:30"},{"start_time":"14:00", "end_time":"16:30"},{"start_time":"17:00", "end_time":"18:00"}]

I am wondering what is the best logical way to do it.

Thanks

Answer 1

function subtract(t1, t2){
     return [{'start_time': t1.start_time, 'end_time': t2.start_time}, 
               {'start_time': t2.end_time, 'end_time': t1.end_time}]
}