JSFiddle - React, Tailwind, and code Playground

HTML

<div id="date"></div>
<div id="getTime"></div>

JavaScript

var prev1 = new Date(), prev2 = new Date().getTime();
setInterval(function() {
    var curr1 = new Date(), curr2 = new Date().getTime();
    document.getElementById("date").innerHTML = "Date(): " + (curr1 - prev1) + "ms";
    document.getElementById("getTime").innerHTML = "Date().getTime(): " + (curr2 - prev2) + "ms";
    prev1 = curr1;
    prev2 = curr2;
}, 500);