As I slowly make my way into the land of ES6 (sure I started mid-2016 when all the cool kids were doing it for years) I've been presented with the problem of: when do you use
const and when do you use
let and do I still use
TL,DR: always use
const, except for primitives whose value will change, then use
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🚮 var: no more
var at all. Which sucks, because I've got over 17 years of muscle memory writing
Which is sort of sad because now I can't do any magic hoisting. Which, in fact is almost enough by itself to stop using
var. However, we also now have
let to define variables and
var really isn't needed.
Honestly, I can't see the need for this (again, context is Node) at all anymore…maybe I'm wrong?
💎 const: always, but not always
The first important thing to always keep in mind when using
const is that it's not really really constant. Or more specifically, it doesn't make objects immutable.
The best way (I've found) to think of
const is that the variable that you assign with
const is an immutable pointer. Primitive types, such as strings, booleans and numbers can't be changed - since the variable is pointing directly at the primitive (so you can't do
const a = 10; a++). Objects and arrays on the other hand, can have their properties changed.
However, it's been argued by many that using
const is a way to document your intent with a variable to a future reader of the code. My thoughts: always use
☔️ let: the exception
Assuming you (or I) only use
const, the only exception is when I know that the variable's contents will change. For instance, in a
for loop, or some dynamic allocation. Then, and only then, do I need to use
Filing this post under "stuff I shoulda learnt 18 months ago"