```ts

function mergeIntervals(intervals: number[][]): number[][] {
  if (intervals.length === 0) return [];

  intervals.sort((a, b) => a[0] - b[0]);

  const mergedIntervals = [intervals[0]];
  let currentInterval = intervals[0];

  for (let i = 1; i < intervals.length; i++) {
    if (intervals[i][0] > currentInterval[1]) {
      mergedIntervals.push(intervals[i]);
      currentInterval = intervals[i];
    } else {
      currentInterval[1] = Math.max(currentInterval[1], intervals[i][1]);
    }
  }

  return mergedIntervals;
}
```