JSFiddle - React, Tailwind, and code Playground

by Walter Rumsby

HTML

<code>foo</code>

<table>
  <tr>
    <td>
      <code>foo.email</code>
    </td>
    <td id="foo_email"></td>
    <td id="foo_email_value"></td>
  </tr>
  <tr>
    <td>
      <code>foo.hasOwnProperty('email')</code>
    </td>
    <td id="foo_hasownproperty_email"></td>
  </tr>
</table>

JavaScript

const Foo = function (name) {
  this.name = name;
};

Foo.prototype = {
	email: undefined
};


const foo = new Foo('test');

foo.email = undefined;

document.getElementById('foo_email').innerHTML = foo.email ? 'true' : 'false';

document.getElementById('foo_email_value').innerHTML = '' + foo.email;

document.getElementById('foo_hasownproperty_email').innerHTML = foo.hasOwnProperty('email') ? 'true' : 'false';