JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fulltext">
[test="data/ft-file/images/small/red"]
</div>

JavaScript

let text = document.getElementsByClassName("fulltext")[0].innerHTML;
var reg = /^ft-file$/;

if (reg.test(text) == true) {
    console.log("true");
} else {
    console.log("false")
}