Monotonic Array

LeetCode 題目: 896. Monotonic Array

My solution:

/**
 * @param {number[]} nums
 * @return {boolean}
 */
let isMonotonic = nums => {
  let monotonic = {
      increasing: false,
      decreasing: false
  }
  for(let i=0; i<nums.length; i++){
      if(nums[i] > nums[i-1]) monotonic.increasing = true;
      if(nums[i] < nums[i-1]) monotonic.decreasing = true;
      if(monotonic.increasing && monotonic.decreasing) return false;
  }
  return true;    
};