JSFiddle - React, Tailwind, and code Playground
HTML
<div class="text">
Concept number 1: my content here1<br>
Concept number 2: my content here2<br>
Concept number 3: my content here3<br>
</div>JavaScript
var text = $('.text').html();
var regex = new RegExp('Concept number 1:(.*?)<br>', "g");
var matches = text.match(regex);
console.log(text);
console.log(matches);