my_solution.js

/**
 * @param {number[][]} intervals
 * @return {number[][]}
 */
const merge = (intervals) => {
  if (1 === intervals.length) return intervals;
  let result = [];

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


  while (0 < intervals.length) {
    let curr = intervals.shift();
    if (0 === result.length) {
      result.push(curr);
      continue;
    }

    let prev = result[result.length - 1];
    if (prev[1] >= curr[0]) {
      result.pop();
      result.push([Math.min(prev[0], curr[0]), Math.max(prev[1], curr[1])]);
    } else {
      result.push(curr);
    }
  }

  console.log(result)

  return result;
};


let x = merge([[1, 2], [3, 7], [4, 7], [8, 10], [15, 18]]);
// let x = merge([[1, 3], [8, 10], [2, 6], [15, 18]]);
// let x = merge([[1, 3]]);
// let x = merge([[1, 4], [5, 6]]);
console.log(x)