PHP Slug Generation Function Giving Improper Output

Question

I am using below code to get a proper slug that I am sending from an ajax call.

$slug = strtolower(trim(preg_replace('/[^A-Za-z]+/', '-', $_POST['slug'])));

But, what's happening is. If from an ajax request I am getting any slug-like

slug: top-5-ways--to-avoid-list-

I want to trim unwanted - hyphens and any numeric values from the slug and want the below slug

slug: top-ways-to-avoid-list

I am not able to understand that what is wrong with the code.

Answer 1

slugify your string this way, it'll remove unwanted characters including -.

trim() takes as 2nd parameter all characters that you want to be stripped. So have a look on the commented line THIS WILL FIX YOUR EXISTING PROBLEM

<?php
function slugify($string, $delimiter = '-'){
  $clean = preg_replace("/[^a-zA-Z\/_|+ -]/", '', $string); 
  $clean = strtolower($clean);
  $clean = preg_replace("/[\/_|+ -]+/", $delimiter, $clean);
  $clean = trim($clean, $delimiter); // THIS WILL FIX YOUR EXISTING PROBLEM
  return $clean;
}

echo slugify('-Top ways-to avoid list-');
echo PHP_EOL;
echo slugify('top 5 ways to get in top');
?>

Output:

top-ways-to-avoid-list 
top-ways-to-get-in-top

DEMO: https://3v4l.org/ljtlZ

OR with your existing code trimming multiple characters - or spaces

<?php
echo strtolower(trim(preg_replace('/[^A-Za-z]+/', '-', '-Top ways-to avoid list-'),'- '));
echo PHP_EOL;
echo strtolower(trim(preg_replace('/[^A-Za-z]+/', '-', 'top 5 ways to get in top'),'- '));
?>

DEMO: https://3v4l.org/aBtHI