difference between undefined and null

What is the Difference between Undefined, undeclared, Null

// undefined means that the variable has not been declared, or has not been given a value.
// Undefined is used for unintentionally missing values.
var dog;
console.log(dog);


// Undeclared means the variable does not exist in the program at all.
console.log(cat);


// Null used for intentionally missing values. It contains no value.

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Contributed on May 31 2022

Yafet Segid

0 Answers Avg Quality 2/10

difference between undefined and null?

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null is a special object because typeof null returns 'object'. 
On the other hand,
undefined means that the variable has not been declared,
or has not been given a value.

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Contributed on Jul 10 2021

Good Gnu

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difference between undefined and null javascript

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undefined: It means a variable declared, but no value has been assigned a value.

//example: 
var demo;
alert(demo); //shows undefined
alert(typeof demo); //shows undefined

null: Whereas, null in JavaScript is an assignment value. 
You can assign it to a variable.

//Example: 
var demo = null;
alert(demo); //shows null
alert(typeof demo); //shows object

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Contributed on Jun 20 2022

Rasel Ahmed

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null vs undefined

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//loosely equal (compare values between two variables)
null == undefined // true  ( null => 0 , undefined => NAN)

//strictly not equal (compare both type and value) 
null === undefined // false  (typeof null => object , typeof undefined => undefined)
null !== undefined // true   (typeof null => object , typeof undefined => undefined)

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Contributed on Aug 12 2021

Jaimin Patel

0 Answers Avg Quality 2/10

difference between undefined and null

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