Array Is Sorted

Introduction

In this lab, we will be working with the isSorted function in JavaScript to determine whether a numeric array is sorted in ascending or descending order. We will use the Math.sign() method to convert the final direction value to -1 for descending order and 1 for ascending order. We will also handle cases where the array is empty, has only one element, or the direction changes for any pair of adjacent array elements.

Skills Graph

Code Practice: Check if an Array is Sorted

To practice coding, open the Terminal/SSH and type node.

Here's a function to check if a numeric array is sorted:

const isSorted = (arr) => {
  if (arr.length <= 1) return 0;
  const direction = arr[1] - arr[0];
  for (let i = 2; i < arr.length; i++) {
    if ((arr[i] - arr[i - 1]) * direction < 0) return 0;
  }
  return Math.sign(direction);
};

To use it, pass an array of numbers to isSorted(). The function will return 1 if the array is sorted in ascending order, -1 if it's sorted in descending order, and 0 if it's not sorted.

Here are some examples:

isSorted([0, 1, 2, 2]); // 1
isSorted([4, 3, 2]); // -1
isSorted([4, 3, 5]); // 0
isSorted([4]); // 0

Summary

Congratulations! You have completed the Array Is Sorted lab. You can practice more labs in LabEx to improve your skills.