Creating User and SEO friendly URL slug in PHP and JavaScript

user_seo_friendly_slug.php

<?php
function slug($data, $max_length = 100){
	// Convert the string to lowercase
	$string = mb_strtolower($data, 'UTF-8');

	// Create a transliterator for UTF-8 to ASCII
	$transliterator = Transliterator::create('NFD; [:Nonspacing Mark:] Remove; NFC; Any-Latin; Latin-ASCII;');

	// Transliterate the string
	$string = $transliterator->transliterate($string);

	// Replace spaces with dashes, remove special characters
	$string = preg_replace('/[^\p{L}\p{N}\s-]/u', '', $string);
	$string = trim(preg_replace('/\s+/', '-', $string));

	// Remove unwanted characters
	$string = preg_replace('/[^a-z0-9-]/', '', $string);

	// Remove duplicate dashes
	$string = preg_replace('/-+/', '-', $string);

	// trim to max_length
	$string = mb_substr($string, 0, $max_length, 'UTF-8');

	// Return the URL slug
	return $string;
}