JSFiddle - React, Tailwind, and code Playground

by Chris Rebert

HTML

<ul>
    <li>Can createEvent?: <span id="canCreate"></span></li>
    <li>window.CustomEvent exists?: <span id="global"></span></li>
    <li>CustomEvent constructor? <span id="construct"></span></li>
</ul>

JavaScript

var created = false;
try {
    var event1 = document.createEvent('CustomEvent');
    created = true;
}
catch (e) {
    created = false;
}
$('#canCreate').text(created ? "PASS" : "FAIL");

var globalExists = window.CustomEvent !== undefined;
$('#global').text(globalExists ? "PASS" : "FAIL");

var cons = false;
if (globalExists) {
    try {
        var event2 = new CustomEvent('bark');
        cons = true;
    }
    catch (e) {
        cons = false;
    }
}
else {
    cons = false;
}
$('#construct').text(cons ? "PASS" : "FAIL");