```ts
export function mergeIntervals(intervals: number[][]): number[][] {
  if (!intervals.length) return [];

  // Sort intervals by start time
  intervals.sort((a, b) => a[0] - b[0]);

  let merged: number[][] = [intervals[0]];

  for (let i = 1; i < intervals.length; i++) {
    const lastMerged = merged[merged.length - 1];

    if (lastMerged[1] >= intervals[i][0]) {
      // Intervals overlap, merge
      lastMerged[1] = Math.max(lastMerged[1], intervals[i][1]);
    } else {
      // Add the current interval as a new interval
      merged.push(intervals[i]);
    }
  }

  return merged;
}
```