function arrayMaximalAdjacentDifference(nums) {
  if (!Array.isArray(nums) || !nums.length) {
    throw new Error("Invalid argument");
  }

  if (nums < 2) return nums[0];

  let maxAbsoluteDiff = Math.abs(nums[0] - nums[1]);
  const lastIndex = nums.length - 1;

  for (let i = 1; i < lastIndex; i += 1) {
    const diff = Math.abs(nums[i] - nums[i + 1]);
    if (maxAbsoluteDiff < diff) {
      maxAbsoluteDiff = diff;
    }
  }

  return maxAbsoluteDiff;
}



/**
* Test Suite 
*/
describe('arrayMaximalAdjacentDifference()', () => {
    it('returns largest difference between adjacent values', () => {
        // arrange
        const nums = [2, 4, 1, 0];
        
        // act
        const result = arrayMaximalAdjacentDifference(nums);

        // log
        console.log("result 1: ", result);
        
        // assert
        expect(result).toBe(3);
    });

    it('returns largest difference between adjacent values example 2', () => {
        // arrange
        const nums = [2, 9, 1, 0];
        
        // act
        const result = arrayMaximalAdjacentDifference(nums);

        // log
        console.log("result 2: ", result);
        
        // assert
        expect(result).toBe(8);
    });
});