35. 搜索插入位置

var searchInsert = function (nums, target) {
  if (nums.length === 0) {
    return 0
  }
  if (nums[0] >= target) {
    return 0
  }
  if (nums[nums.length - 1] < target) {
    return nums.length
  }
  let left = 0,
    right = nums.length - 1,
    mid = 0
  while (left <= right) {
    mid = Math.floor((left + right) / 2)
    if (nums[mid] === target) {
      index = mid
      return index
    } else if (nums[mid] > target) {
      right = mid - 1
    } else if (nums[mid] < target) {
      left = mid + 1
    }
  }
  return nums[mid] >= target ? mid : mid + 1
}