Twig Components / Methods / preg_quote

preg_quote(delimiter = "\/") is a Twig filter to quote regular expression characters. It puts a backslash in front of every character that is part of the regular expression syntax. This is useful if you have a run-time string that you need to match in some text and the string may contain special regex characters.

{% set keywords = '$40 for a g3/400' %}
{{ keywords|preg_quote('/') }}

Result: '\$40 for a g3\/400'

Source: Jasny