How to reformat a number?

Question

PHP

<a class="footer-phone" href="tel:[phone]"><?= CFS()->get('phone', 19) ?></a>

There is a custom field in WP where the admin enters a number in the format [phone] and in the same format it is displayed in place of CFS()->get('phone', 19). But in the href attribute, after tel: the format is [phone]. It is clear that in JS by .replace all unnecessary characters will be removed, but how to accept the value of CFS()->get('phone', 19) from php, pass it to JS and remake + how to make it so that after tel: the "altered" value was inserted automatically, i.e. JS answer?