They both represent a empty value.
Null means an empty or non-existent value.
Null is assigned, and explicitly means nothing. while undefined typically means a variable has been declared but not defined yet.
var a; console.log(a); // undefined var b = null; console.log(b); // null
var a; console.log(typeof(a)); // undefined var b = null; console.log(typeof(b)); // object
As you can see so far, null and undefined are different, but share some similarities. Thus, it makes sense that null does not strictly equal undefined.
console.log(null !== undefined); // true
But, and this may surprise you, null loosely equals undefined.
console.log(null == undefined); // true
See you soon for more tips !