A Common-Sense Guide to Data Structures and Algorithms in JavaScript, Volume 1

Palindrome Checker

A palindrome is a word or phrase that reads the same both forward and backward. Some examples include racecar, kayak, and deified.

Here’s a function that determines whether a string is a palindrome:

function isPalindrome(string) {
  let leftIndex = 0;
  let rightIndex = string.length - 1;

  // Iterate until leftIndex reaches the middle of the array:
  while (leftIndex < Math.floor(string.length / 2)) {
    // If the character on the left doesn't equal the character
    // on the right, the string is not a palindrome:
    if (string[leftIndex] !== string[rightIndex]) {
      return false;
    }

    leftIndex += 1;
    rightIndex -= 1;
  }

  // If we got through the entire loop without finding any
  // mismatches, ...