JSFiddle - React, Tailwind, and code Playground

HTML

Expected result:
<br>
#my-html-wrapper-random #my-html-wrapper-random .main-content
<br>
<br>
Actual result:

JavaScript

var testString = "#my-html-wrapper-random .html-wrap .main-content";
var rxString = ".html-wrap";
var rx = new RegExp(rxString);
var result = testString.replace(rx,"#my-html-wrapper-random");

var resultElement = document.createElement("div");
resultElement.innerText = result;
document.querySelector("body").appendChild(resultElement);