Use const declarations for variables that are never reassigned JS-0242

Variables that are never re-assigned a new value after their initial declaration should be declared with the const keyword. This prevents the programmer from erroneously re-assigning to a read-only variable, and informs those reading the code that a variable is a constant value.

Bad Practice

let pi = Math.PI

for (let x of xs) {
  use(x);
}

let { a, b } = object;
use(a, b);

Recommended

const pi = Math.PI

for (const x of xs) {
  use(x);
}

const { a, b } = object;
use(a, b);