Check if more than two time ranges overlap in angular

Well, the formula for two time ranges is well known: Determine Whether Two Date Ranges Overlap

So, you need to check that this check is verified for any pair, like this:

function areOverlapping(a, b) {
  return (a.startA <= b.end) && (a.end >= b.start);
}

function anyOverlap(intervals: any[]) { 
  for(let i = 0; i < intervals.length - 1; i++) {
    for(let j = i + 1; j < intervals.length; j++) {
      if (areOverlapping(intervals[i], intervals[j])) return true;
    }
  }

  return false;
}

if (anyOverlap([interval1, interval2, interval3])) {
  // there is at least a pair that overlaps.
}