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Null vs Undefined in JavaScript in 1 min

Gopi Krishna on July 23, 2019

Note: It's my first blog post, constructive criticism would be welcome 🙂 I always had a small confusion between null and undefined in JavaScript. ...
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savagepixie profile image
SavagePixie • Edited

You make the statement "If the value is unknown at the time of variable definition, it's always best to use null," but you don't defend it. I think your point would be greatly improved if you explained why null is better than undefined (and so help other people better understand the concept.)

(Edit: unless I have somehow missed it in the article, of course)

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Gopi Krishna

I thought the example explains that. When variables are declared but not initialized, Javascript assigns undefined to it. But when we assign null, we know that it is "empty" or "nothing" and later we can assign some value to it.

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SavagePixie

Yes, that's right. I guess that what I'm trying to understand is more along the lines of why is it bad for your code to have a variable set as undefined? (ie, what sorts of problems does it cause?) and how does setting it to null instead fix or improve it?

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Gopi Krishna

I don't think using null will fix or improve anything, it's just a good practice to follow.

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aminmansuri profile image
hidden_dude

I wonder why we even need an undefined in Javascript. Wouldn't it just be better to default to null?
I fail to see a scenario in which having undefined (vs null) is useful.

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Gopi Krishna
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hidden_dude

yeah.. it just seems to say that having both is a bit redundant.

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sahaj ranipa

Good and neat explanation which will help us to understand the concepts in more interesting way.

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Gopi Krishna

Thank you 🙂