JSFiddle - React, Tailwind, and code Playground

by petroveg

HTML

<span class="cena">102000000руб.</span>
<br/>
<span class="cena">6780070 руб.</span>

JavaScript

$(function () {
    $('.cena').each(function () {
        $(this).text($(this).text().replace(/^\s*(\d+)(\d{3})\s*([а-я\.]+)\s*$/, '$1 $2 $3'));
    });
});