JSFiddle - React, Tailwind, and code Playground

JavaScript

var foo = {};
Object.defineProperty(foo, "bar", { 
    "get": function () {document.write("Getter invoked!<br/>"); return foo;}
});

document.write('"bar" in foo -->' + ("bar" in foo));
document.write('<br/>');
document.write('typeof foo["bar"] !== "undefined" -->' + (typeof foo["bar"] !== "undefined"));
document.write('<br/>');