JSFiddle - React, Tailwind, and code Playground

HTML

<code id="deepUndefined">obj === $.extend(obj, {}): <strong></strong></code>
<code id="deepTrue">obj === $.extend(true, obj, {}): <strong></strong></code>
<code id="deepFalse">obj === $.extend(false, obj, {}): <strong></strong></code>

CSS

code { display: block; margin: 1em 0; }

JavaScript

var obj;

obj = {};
$("*", "#deepUndefined").text(obj === jQuery.extend(obj, {}));

obj = {};
$("*", "#deepTrue").text(obj === jQuery.extend(true, obj, {}));

obj = {};
$("*", "#deepFalse").text(obj === jQuery.extend(false, obj, {}));