JSFiddle - React, Tailwind, and code Playground

HTML

<input id="date" type="text" value="2011-08-20">
<button id="btn">Click me!</button>

JavaScript

$("#btn").click(function() {
    var aDate = $("#date").val().split('-');
    var epoch = new Date(aDate[0], aDate[1] - 1, aDate[2]).getTime() / 1000;
    alert("Date:\t" + aDate.toString() + "\nEpoch:\t" + epoch.toString());
});