Convert JQuery RegEx into PHP RegEX - php

Question

Sorry for this question as it is very specific.
I have a JQuery validation RegEx that I would like to use on the back end too:
var forNames = new RegExp("^[^0-9<>'\"/;`%]*$");
I tried in PHP
preg_match('/^[^0-9<>\'\"/;`%]{2,42}$/', $first_name) // I also want to keep the length between 2 and 42 here)
but it does not work, I get Unknown modifier ';' in
The other question, similar to this one is what this person is asking here
Converting Javascript Regex to PHP
I tried his solution, copying the php email validation regex into JQuery with no luck
Thank you
Ps I just unedited what i had added to the regex cause i didnt see it already had answers and it was confusing

Answer 1

You need to escape the / character in your PHP regex string, because that's also the character which is used to signify the end of a regexp (it's called a delimiter):
preg_match('/^[^0-9<>\'\"/;`%]{2,42}$/', $first_name)
^
becomes:
preg_match('/^[^0-9<>\'\"\/;`%]{2,42}$/', $first_name)
The reason you didn't need to do this in your JavaScript code is that you used the RegExp constructor, which essentially automatically escaped it for you. If you had used a RegExp literal you would have had to escape it too:
var forNames = /^[^0-9<>'\"\/;`%]*$/;
As #DelightedD0D commented, make sure to test your RegExp with an interactive tool like regex101, it supports both PHP and JS style regexp and is actually how I was able to catch your error so fast.