Palindrome String Checker

Determining if a string is a palindrome is a classic programming exercise. A palindrome is a string that reads the same forwards and backward, ignoring case and non-alphanumeric characters. This challenge will test your ability to manipulate strings and implement a robust palindrome check in JavaScript.

Problem Description

You are tasked with creating a JavaScript function called isPalindrome that takes a single string as input and returns true if the string is a palindrome, and false otherwise. The function should ignore case and non-alphanumeric characters (letters and numbers only) when determining if the string is a palindrome. This means spaces, punctuation, and other special characters should be removed before the check.

Key Requirements:

• The function must accept a string as input.
• The function must return a boolean value (true or false).
• Case should be ignored (e.g., "Racecar" should be considered a palindrome).
• Non-alphanumeric characters should be ignored (e.g., "A man, a plan, a canal: Panama" should be considered a palindrome).
• The function should handle empty strings and strings with a single character correctly.

Expected Behavior:

The function should accurately identify palindromes and non-palindromes based on the criteria outlined above.

Examples

Example 1:

Input: "Racecar"
Output: true
Explanation: The string "Racecar" reads the same forwards and backward, ignoring case.

Example 2:

Input: "A man, a plan, a canal: Panama"
Output: true
Explanation: After removing non-alphanumeric characters and converting to lowercase, the string becomes "amanaplanacanalpanama", which is a palindrome.

Example 3:

Input: "hello"
Output: false
Explanation: The string "hello" does not read the same forwards and backward.

Example 4:

Input: ""
Output: true
Explanation: An empty string is considered a palindrome.

Example 5:

Input: "a"
Output: true
Explanation: A single-character string is considered a palindrome.

Constraints

• The input string can contain any ASCII characters.
• The input string's length can be up to 1000 characters.
• The function should execute in a reasonable time (e.g., less than 100ms for strings of length 1000).

Notes

• Consider using regular expressions to efficiently remove non-alphanumeric characters.
• Think about how to handle case-insensitive comparisons.
• A two-pointer approach (one starting from the beginning and one from the end of the string) can be an efficient way to check for palindromes.
• Remember to handle edge cases like empty strings and single-character strings.