JSFiddle - React, Tailwind, and code Playground
HTML
<div id="q1">
</div>
<div id="q2">
</div>
<div id="q3">
</div>
<div id="q4">
</div>
<div id="q5">
</div>
CSS
#q7{background-color:#eee; }
JavaScript
var element = document.getElementById('q4');
element.setAttribute('id', 'q7');
if(document.getElementById('q7').innerHTML = "All is well")
alert(document.getElementById('q7').innerHTML);