JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" name="name" id="name">
<button onclick="show_text()" >Absenden</button>
<div style="font-size:20px;" id="output"></div>
JavaScript
function show_text(){
var name = document.getElementById("name").value;
var output = document.getElementById("output");
var html = "Hallo " + name + "!";
output.innerHTML = html;
}