JS: Merge sort (post-holidays exercise)

index.ts

const merge = (left: number[], right: number[]): number[] => {
  let result = []
  let lindex = 0
  let rindex = 0

  while (lindex < left.length && rindex < right.length) {
    if (left[lindex] < right[rindex]) {
      result.push(left[lindex])
      lindex++
    } else {
      result.push(right[rindex])
      rindex++
    }
  }

  return [...result, ...left.slice(lindex), ...right.slice(rindex)]
}

const mergeSort = (arr: number[]): number[] => {
  if (arr.length <= 1) {
    return arr
  }

  const middle = Math.floor(arr.length / 2)
  const left = arr.slice(0, middle)
  const right = arr.slice(middle)
  return merge(mergeSort(left), mergeSort(right))
}

const random = (min: number, max: number) => {
  return Math.floor(Math.random() * (max - min) + min)
}

const numbers = Array.from({ length: 100 }).map(() => random(0, 500))

console.log(mergeSort(numbers))