JSFiddle - React, Tailwind, and code Playground

HTML

<p>
The button click handler bound with mootools will always have preventDefault. Mootools adds it if the browser doesn't have it natively.
</p>

<button id="mootoolsbutton">mootoolsbutton</button>

<p>
If you use onclick attribute on the HTML element you will get the default browser event, which for IE lacks the preventDefault() method. It works fins in Firefox and Chrome.
</p>

<button id="htmlbutton" onclick=" alert(typeof(event.preventDefault)); alert($.event.fix(event).preventDefault);
">htmlbutton</button>

JavaScript

$("mootoolsbutton").addEvent('click', function(event) {
 alert(typeof(event.preventDefault));
});