5 ms·

const vs let is an "immutable by default" vs "mutable by default" type of difference. it's not just a style difference, it can help you write stateless code if

const vs let is an "immutable by default" vs "mutable by default" type of difference. it's not just a style difference, it can help you write stateless code if you assume immutability. but yeah.

BinaryIdiot 10y ago
> const vs let is an "immutable by default" vs "mutable by default" type of difference Sorta. I mean you're right but at the same time if you're using const for an object or array then it doesn't really matter without `object.freeze()` because it's not immutable only the reference is and I don't think most JavaScript developers understand that (at least not most of the ones I've run into).
- gotofritz 10y ago
  Note that Object.freeze only works for shallow objects
deleted 10y ago
[deleted]
z3t4 10y ago
Native objects in JavaScript are already immutable as in you can not change them, only create new objects. Const will not make your object immutable! Try this: const foo = {bar: 1} foo.bar = 2; It will only avoid having the pointer re-pointed to another object. It's better to just try avoiding global variables, and use a naming convention like uppercase and/or underscore for constants and global variables. Const is probably only meant for constants like the name suggests. I think something like this is pretty safe from reassigning: { let foo = 1 ... } ... If you want more control over your properties, you can use the ES5 feature "defineproperty" where you can set writeable: false
- fryan 10y ago
  const foo = {bar: 1} The only thing const about it is the reference `foo` cannot be reassigned: foo = something_else; // error Unlike `const` in C++, `const` in javascript in not very useful in my opinion. `let` is shorter and more readable.
- betenoire 10y ago
  All true. But what I said was, > it can help you write stateless code if you assume immutability
- gotofritz 10y ago
  Even that is only true for shallow objects
- hajile 10y ago
  You can call `Object.freeze()` if you want immutable properties.

const vs let is an "immutable by default" vs "mutable by default" type of difference. it's not just a style difference, it can help you write stateless code if you assume immutability. but yeah.

BinaryIdiot 10y ago

> const vs let is an "immutable by default" vs "mutable by default" type of difference Sorta. I mean you're right but at the same time if you're using const for an object or array then it doesn't really matter without `object.freeze()` because it's not immutable only the reference is and I don't think most JavaScript developers understand that (at least not most of the ones I've run into).

gotofritz 10y ago
Note that Object.freeze only works for shallow objects

deleted 10y ago

[deleted]

z3t4 10y ago

Native objects in JavaScript are already immutable as in you can not change them, only create new objects. Const will not make your object immutable! Try this: const foo = {bar: 1} foo.bar = 2; It will only avoid having the pointer re-pointed to another object. It's better to just try avoiding global variables, and use a naming convention like uppercase and/or underscore for constants and global variables. Const is probably only meant for constants like the name suggests. I think something like this is pretty safe from reassigning: { let foo = 1 ... } ... If you want more control over your properties, you can use the ES5 feature "defineproperty" where you can set writeable: false

fryan 10y ago
const foo = {bar: 1} The only thing const about it is the reference `foo` cannot be reassigned: foo = something_else; // error Unlike `const` in C++, `const` in javascript in not very useful in my opinion. `let` is shorter and more readable.
betenoire 10y ago
All true. But what I said was, > it can help you write stateless code if you assume immutability
gotofritz 10y ago
Even that is only true for shallow objects
hajile 10y ago
You can call `Object.freeze()` if you want immutable properties.