Question

What is the difference between null and undefined in JavaScript

Answer 1

let a = null;
console.log(a); 


let b;
console.log(b); 


 
 
 
/*
run:
 
null
undefined
 
*/

 

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Answer 2

console.log(typeof null); 

console.log(typeof undefined); 

 
 
 
/*
run:
 
"object"
"undefined"
 
*/

 

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Answer 3

console.log(null === undefined); // identity

console.log(null == undefined); // equality



 
 
 
/*
run:
 
false
true
 
*/

 

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Answer 4

console.log(null === null); // identity

console.log(null == null); // equality


 
 
 
/*
run:
 
true
true
 
*/

 

70+ SQL courses for beginners and professionals

Answer 5

console.log(null); 
console.log(undefined);

console.log(!null); 
console.log(!undefined);


 
 
 
/*
run:
 
null
undefined
true
true
 
*/

 

70+ SQL courses for beginners and professionals