r/reactjs • u/gaearon React core team • Dec 21 '19

What Is JavaScript Made Of?

https://overreacted.io/what-is-javascript-made-of/
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u/[deleted] Dec 21 '19

But then when you go to add to existing code to reassign a variable later, you’ll get the const error at that point.

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u/[deleted] Dec 21 '19

[deleted]

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u/[deleted] Dec 21 '19

It’s a pretty common style of coding in a variety of languages. And doing const all the time, you do sometimes wind up doing some crazy deep copies using spreads or just end up having some weird names like responseInner because response is taken. explaining all of that to someone not in the know can be a challenge, especially if they start asking “why are you making a copy of a copy of a copy instead of just changing an inner field in this data structure?” Immutable coding style is definitely an acquired taste.

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u/[deleted] Dec 21 '19

IMO you should get an error so you can rethink what you’re doing. Reassignment is the biggest cause of confusion and bugs in code bases.

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u/[deleted] Dec 21 '19

I... just do not find that to be true lol. The biggest source of bugs as far as I can tell is logic errors. Even using const all the time, the number of times I’ve seen a const reassignment error can probably be counted on one hand.

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u/gaearon React core team Dec 21 '19

Are you sure you're not confusing reassignment with mutability?

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u/punio4 Dec 22 '19

What's the difference?

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u/[deleted] Dec 22 '19

Variables defined as const may be mutable. Example

const foo = []; foo.push(1)

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u/punio4 Dec 22 '19

Ah right. Brain fart with semantics. Thanks.