JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://broofa.com/Tools/JSLitmus/JSLitmus.js"></script>
<div id="foo">first</div>

JavaScript

var str = "match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match match";
var regex = /match/g;
JSLitmus.test("while-exec", function() {
    while (m=regex.exec(str)){
        str = str.substring(0, m.index) + "test";
    }
    document.getElementById("foo").innerHTML = str;
});
JSLitmus.test("match-replace", function() {
    str = str.replace(regex, "testmatch");
    document.getElementById("foo").innerHTML = str;
});