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In this video you will learn about null and undefined in JavaScript. This video will explain similarity and differences between null and undefined

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5 thoughts on “Video: What is null and undefined in JavaScript?

  1. Don’t provide this kind of information buddy check the following :

    1. null is not an object, it is a primitive value. You cannot add properties to it. We wrongly assume that it is an object, because typeof null returns “object”. But that is actually a bug in language itself(check this : http://www.ecma-international.org/ecma-262/5.1/#sec-11.4.3)

    2. Primitive value is a member of one of the following built-in types: Undefined, Null, Boolean, Number, and String; (this statemnt is directly from ECMA-262 (ECMAScript Language Specification))

    3. null is actually used to represent the absence of a value not “undefined”, but Javascript assigns undfined to any variable that is not initialized.

    4. Basically null value means a variable has been explicitly set as (no value = null) or has been initialized and defined to be nothing. While undefined means, it was probably never initialized or if it was it was never defined.

    5. Never ever use the == operator to check the equality in Javascript which actually perform type correcion before comparing the variables so obviously you will wrong results (use only ==== which will compare both the values & type – check ECMA-262 specs).

  2. I don’t agree with your points. I used == to demo that they represent almost same value. and yes null is an object

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