I have the following dates in utc timestamps. I would like to know whether the two time ranges overlap. Here's the code that I have so far:
dateRangeOverlaps(aStart, aEnd, bStart, bEnd) {
if (aStart <= bStart && bStart <= aEnd) return true; // b starts in a
if (aStart <= bEnd && bEnd <= aEnd) return true; // b ends in a
if (bStart < aStart && aEnd < bEnd) return true; // a in b
return false;
}
Unfortunately, when the start times or end times overlap, the function returns true. For example, if I have the times: 9 am to 11am and 11am to 1pm, these two times should not overlap, but the function returns true nonetheless.
Or if I have the time 8am to 11am and 11am to 1pm, it returns true.
How can I make it return false for the times above?
so
// 11:00
const aStart = 1641052800000;
// 11:30
const aEnd = 1641054600000;
// 9:00
const bStart = 1641045600000;
// 11:00
const bEnd = 1641052800000;
// should return false
console.dir(dateRangeOverlaps(aStart, aEnd, bStart, bEnd))
If you fill the example to the code (9 am to 11am and 11am to 1pm), you can easily see the reason:
dateRangeOverlaps(aStart, aEnd, bStart, bEnd) {
if (9am <= 11am && 11am <= 11am) return true; // returns true
// ...
}
I would change the logic to following to make it easier to read:
function dateRangeOverlaps(aStart, aEnd, bStart, bEnd) {
// Make sure aStart is before bStart
if (aStart > bStart) {
// Exchange a and b
[aStart, aEnd, bStart, bEnd] = [bStart, bEnd, aStart, aEnd]
}
// Check overlap
return aEnd > bStart
}
See this answer for a more efficient method.