Exploring Palindrome Numbers with JavaScript: A Step-by-Step Guide

Leetcode: 9. Palindrome Number

Palindrome numbers are fascinating mathematical constructs that read the same backward as forward (e.g., 121, 1331, 1221). In this article, we’ll dive into a JavaScript code snippet that determines whether a given number is a palindrome or not. We’ll break down the code step by step, providing explanations for each segment.

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    let ref = 0;
    let temp = x;
    while(x > 0)
    {
        ref = ref*10 + x%10;
        x = Math.floor(x/10);
    }
    if(ref == temp)
    {
        return true;
    }
    return false
};

Explanation

Function Definition

• var isPalindrome = function(x): This line defines a JavaScript function named isPalindrome that takes a single parameter x, which is expected to be a number.

Variable Initialization

• let ref = 0; and let temp = x;: Two variables ref and temp are initialized. ref is set to 0, and temp is assigned the value of x. These variables are used to store intermediate and original values of x respectively.

While Loop

• while(x > 0) {...}: This initiates a while loop. The loop condition checks if x is greater than 0.

Loop Body

• Inside the while loop, two operations are performed:
• ref = ref * 10 + x % 10;: This line appends the last digit of x to ref by multiplying ref by 10 and adding the remainder of x divided by 10.
• x = Math.floor(x / 10);: This updates x by removing its last digit (using integer division).

Checking for Palindrome

• if(ref == temp) {...}: After the loop terminates, the code checks if ref (which now contains the reverse of x) is equal to temp (the original value of x).

Return Statement

• return true; and return false;: Depending on the result of the comparison, the function returns true if x is a palindrome and false otherwise.

Conclusion

In this article, we’ve examined a JavaScript function that checks if a given number is a palindrome. We dissected each component of the code to provide a clear understanding of how it operates. By employing techniques like loops and basic arithmetic operations, this function efficiently determines whether a number exhibits the intriguing property of palindromicity. This code serves as a valuable resource for both learning JavaScript and exploring the fascinating world of palindromic numbers.