Undefined and null
![[Pasted image 20240112165745.png]]
undefined
means a variable has been declared but has not yet been assigned a value :
var testVar;
console.log(testVar); //shows undefined
console.log(typeof testVar); //shows undefined
null
is an assignment value. It can be assigned to a variable as a representation of no value :
var testVar = null;
console.log(testVar); //shows null
console.log(typeof testVar); //shows object
From the preceding examples, it is clear that undefined
and null
are two distinct types: undefined
is a type itself (undefined) while null
is an object.