JSFiddle - React, Tailwind, and code Playground

HTML

<div id="log"></div>

JavaScript

var a = {
    foo: function(word){
        this.foo.bar = word;
    }
};
a.foo.bar = "yeah";

var b = $.extend(true,{},a);

var log = ["b.foo.bar = [" + b.foo.bar + "]" + " (should be 'yeah') <br/>"];

a.foo("PHO SOUP");

log.push( "b.foo.bar = [" + b.foo.bar + "]" + " (should still be 'yeah')");

$("#log").html(log.join(""));