JSFiddle - React, Tailwind, and code Playground
HTML
<span id="foo">blah blaah blaaah blaaaaaaah</span> has <span id="bar"></span> matches
JavaScript
$("#bar").text($("#foo").text().match(/(.)\1\1+/g).length)
<span id="foo">blah blaah blaaah blaaaaaaah</span> has <span id="bar"></span> matches
$("#bar").text($("#foo").text().match(/(.)\1\1+/g).length)