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Why typeof NULL is return undefined while typeof null return object ?

Check this snippet

console.log(typeof NULL)// undefined 

console.log(typeof null)// object 

Why typeof NULL is return undefined while typeof null return object ?

Check this snippet

console.log(typeof NULL)// undefined 

console.log(typeof null)// object 

• javascript
• typeof

Share Improve this question Follow edited Aug 2, 2018 at 8:21 leogoesger 3,84077 gold badges3838 silver badges7474 bronze badges asked Aug 2, 2018 at 7:52 Ramesh RajendranRamesh Rajendran 38.7k4949 gold badges159159 silver badges240240 bronze badges 1

• isn't that because js is case-sensitive? safaribooksonline./library/view/javascript-the-definitive/… – leogoesger Commented Aug 2, 2018 at 7:54

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3 Answers 3

Sorted by: Reset to default 7

JavaScript is case-sensitive, so they are two different things:

NULL is a variable, which is not defined.

null is the null-object.

JavaScript is a case-sensitive language. This means that language keywords, variables, function names, and any other identifiers must always be typed with a consistent capitalization of letters. The while keyword, for example, must be typed “while”, not “While” or “WHILE”. Similarly, online, Online, OnLine, and ONLINE are four distinct variable names.

So NULL is a variable that you have not defined yet, whereas null is

The value null represents the intentional absence of any object value.

To read more:

https://www.safaribooksonline./library/view/javascript-the-definitive/0596000480/ch02s02.html

https://developer.mozilla/en-US/docs/Web/JavaScript/Reference/Global_Objects/null

NULL and null do not reppresent the same thing, since it is case sensitive.

Check here the reference:

https://developer.mozilla/en-US/docs/Web/JavaScript/Reference/Global_Objects/null

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