Strings & Text

JavaScript Program to Check Palindrome

Determine if a word, phrase, or number reads identically backwards and forwards in JavaScript while ignoring non-alphanumeric characters.

JavaScript Source Code

Editable code sample with line numbers

JavaScript

Expected Output

When this program is compiled and executed, the terminal outputs:

"A man, a plan, a canal: Panama" => PALINDROME
"race a car" => NOT A PALINDROME
"level" => PALINDROME
"ZenCompiler" => NOT A PALINDROME

How the Code Works

We first clean the input string using a regular expression /[^a-z0-9]/g to strip all whitespace and punctuation, then normalize characters to lowercase. A two-pointer approach checks characters from outer ends towards the center. If any mismatch occurs, it returns false early without completing unnecessary iterations.

Time Complexity

O(N)

Space Complexity

O(N) for cleaned string

Key Takeaways & Best Practices

Regex sanitation is crucial for phrase-level palindromes.
Two-pointer search allows early termination on first mismatch.

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