JSFiddle - React, Tailwind, and code Playground

HTML

<input id="btn" type="button" value="click me" />

JavaScript

function click_handler()
{
    alert("clicked");
}
var el = document.getElementById("btn");   
if(el.addEventListener)//check if this exists
{
    el.addEventListener("click", click_handler);   
} else {
    //then we're on IE older than 9
    el.attachEvent("onclick",click_handler);
}