no-var.md

Pattern: Use of var declaration

Issue: -

Description

The var keyword creates function-scoped variables that can be accessed before declaration due to hoisting. Using let and const provides better scoping rules and prevents temporal dead zone issues common with var.

Examples

Example of incorrect code:

var x = 10;
var config = {};
var i;
for (var j = 0; j < 10; j++) {
  setTimeout(() => console.log(j));
}

function example() {
  var tmp = 'value';
}

Example of correct code:

let x = 10;
const config = {};
let i;
for (let j = 0; j < 10; j++) {
  setTimeout(() => console.log(j));
}

function example() {
  let tmp = 'value';
  const immutable = 'constant';
}