JSFiddle - React, Tailwind, and code Playground

HTML

<h4>This javascript sets the h4 tag with a class of "icontitle" to red</h4>
<h4>Hello World!</h4>
<h4>Hello World!</h4>
<h4>Hello World!</h4>
<h4>Hello World!</h4>
<h4>Hello World!</h4>
<h4>Hello World!</h4>
<h4 class="icontitle">Hello World!</h4>

JavaScript

var myList = document.getElementsByTagName("h4"); // get all p elements

var i = 0;
while(i < myList.length) {
    if(myList[i].className == "icontitle") {
        myList[i].style.color="red";
    }
    i++;
}