What is the difference between undefined value and null value?

Undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value.Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.

Unassigned variables are initialized by JavaScript with a default value of undefined. JavaScript never sets a value to null. That must be done programmatically.

    • Undefined value cannot be explicitly stated that is there is no keyword called undefined whereas null value has keyword called null
    • typeof undefined variable or property returns undefined whereas
      typeof null value returns object