Is there a difference between "let" and "var" in JS?

Question

I'm not quite sure if there is some difference in functions with let and var declaring a variable... pls help

Answer 1

Var :
1. Old
2. Function scoped
3. Hoisted
4. In global scope its added to window/global object.
5. supports redeclaaration

Let:
1. Newer came in 2015 (ES6)
2. Block scoped
3. Not hoisted
4. Its not added like var to global objects
5. throws error during redeclaration

2 and 3 are important to know, hoisting being a bit confusing but explained in code below

https://code.sololearn.com/WdGAFeNRAe9M/?ref=app

https://code.sololearn.com/WiHHHOb3qp8W/?ref=app

Answer 2

The let statement declares a block scope local variable, optionally initializing it to a value.

let allows you to declare variables that are limited in scope to the block, statement, or expression on which it is used. This is unlike the var keyword, which defines a variable globally, or locally to an entire function regardless of block scope.

example code with output in the comments:

function varTest() {
var x = 1;
if (true) {
var x = 2; // same variable!
console.log(x); // 2
}
console.log(x); // 2
}

function letTest() {
let x = 1;
if (true) {
let x = 2; // different variable
console.log(x); // 2
}
console.log(x); // 1
}

[source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let]

Answer 3

@Chrizzhigh so the only difference there is in scoping?

Answer 4

so far i have not read anything else ... but maybe someone else can correct me if i am wrong =)

Answer 5

sure thing 😂