LeetCode: Find First And Last Position Of Element In Sorted Array Solution

1/**
2 * @param {number[]} nums
3 * @param {number} target
4 * @return {number[]}
5 */
6var searchRange = function (nums, target) {
7  const binarySearchLeft = (nums, target) => {
8    let [left, right, index] = [0, nums.length - 1, -1]
9    while (left <= right) {
10      const mid = Math.floor((left + right) / 2)
11      if (nums[mid] >= target) {
12        right = mid - 1
13      } else {
14        left = mid + 1
15      }
16      if (nums[mid] === target) {
17        index = mid
18      }
19    }
20
21    return index
22  }
23  const binarySearchRight = (nums, target) => {
24    let [left, right, index] = [0, nums.length - 1, -1]
25    while (left <= right) {
26      const mid = Math.floor((left + right) / 2)
27      if (nums[mid] <= target) {
28        left = mid + 1
29      } else {
30        right = mid - 1
31      }
32      if (nums[mid] === target) {
33        index = mid
34      }
35    }
36
37    return index
38  }
39
40  return [binarySearchLeft(nums, target), binarySearchRight(nums, target)]
41}
42
43var searchRange = function (nums, target) {
44  return [nums.indexOf(target), nums.lastIndexOf(target)]
45}