Demistifying null and undefined in javascript ?

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What's the difference between undefined and null?

Answer. Similarities between null and undefined.

• In javascript 7 both comes under the primitive type

let primitiveTypes[]= {'string','number','boolean', 'null' , 'undefined' , 'symbol' , 'bigint' }

• when we print both undefined and null they will give "undefined"

console.log(null)

null

console.log(undefined)

undefined

• Lets use ==, === to compare both

console.log(null==undefined)

true

console.log(null === undefined ) 

false

• Undefined is basically assigned when there is the only declaration for the function,variable, class

variable :

let onlyDeclarared

console.log(onlyDeclarared)

output -

undefined

#####function :

const withoutBodyFunc = () => {}
console.log(withoutBodyFunc())


output 

undefined

Object

const someObj = {
  a: 'test',
  b: 'btest',
  c: 'ctest',
}

console.log(someObj['d'])

output 

undefined.