JSFiddle - React, Tailwind, and code Playground
HTML
<p><label>Name:</label>
<input type="text" name="userName" id="userName" value="default value"/>
</p>
<input type="submit" name="submitButton" value="Display" onclick="run()"/>
<p>Name Provided: <label id="outputUserName"></label></p>
JavaScript
var userName = document.getElementById("userName").value;
function run() {document.getElementById("outputUserName").innerHTML = userName;}