JAVASCRIPT
Sanitize Input: Remove Non-Alphanumeric Characters
Clean user input by removing all characters that are not letters or numbers, using a simple and effective JavaScript regex `replace` method.
function sanitizeAlphanumeric(input) {
// Retains only letters (a-z, A-Z) and numbers (0-9).
// The `g` flag ensures all occurrences are replaced, not just the first.
return input.replace(/[^a-zA-Z0-9]/g, '');
}
// Usage:
console.log(sanitizeAlphanumeric('Hello! @World_123.')); // 'HelloWorld123'
console.log(sanitizeAlphanumeric('Special Chars: !@#$%^&*()')); // 'SpecialChars'
How it works: The `sanitizeAlphanumeric` function takes a string and returns a new string containing only alphanumeric characters. It achieves this by using the `replace()` method with a regular expression `/[^a-zA-Z0-9]/g`. The `[^...]` part is a negated character set, meaning it matches any character that is *not* a letter (a-z, A-Z) or a number (0-9). The `g` flag ensures that all non-alphanumeric characters throughout the string are replaced with an empty string.