Javascript null object type

MDN explain it thus:

The value null is a JavaScript literal representing null or an "empty" value, i.e. no object value is present. It is one of JavaScript's primitive values.

The value null is a literal

Further down that page you'll find this:

typeof null        // object (bug in ECMAScript, should be null)
typeof undefined   // undefined
null === undefined // false
null  == undefined // true

Here is a codepen with that very code, showing the results (and the bug talked about)

document.getElementById('test1').innerHTML = typeof null;
document.getElementById('test2').innerHTML = typeof undefined;
document.getElementById('test3').innerHTML = null === undefined;
document.getElementById('test4').innerHTML = null == undefined;

<div id="test1"></div>
<div id="test2"></div>
<div id="test3"></div>
<div id="test4"></div>