What are the differences between null and undefined?

The differences between null and undefined are given below:

Null	Undefined
It indicates that variable points to no object.	It indicates that variable has been declared but not yet assigned a value.
Type of null is object	Type of undefined is undefined
The null value is a primitive value	The undefined value is a primitive value
Indicates the absence of a value for a variable	Indicates absence of variable itself
Converted to zero (0) while performing primitive operations	Converted to NaN while performing primitive operations
var userName; console.log(userName); //shows undefined console.log(typeof userName); //shows undefined	var userName = null; console.log(userName); //shows null console.log(typeof userName); //shows object

Special cases about null and undefined

null === undefined // false
null == undefined // true
null === null // true

null = 'value' // ReferenceError
undefined = 'value' // 'value'