var Vs let in JavaScript

The main difference is the scope rules:

The let variable can only be available inside the scope it's declared, they are scoped to the immediate enclosing block denoted by { }

The var variable belongs to the global scope or the local scope if they are declared inside a function.

There's also a difference when creating global properties.

Example:

var foo = "I'm added to the global obj as a property.";


console.log(window.foo); / /I'm added to the global obj as a property.


let foo = "I'm not added to the global obj as a property."

console.log(window.foo); // undefined . .