Why is this difference between `var` and `let` in firefox web console but not in node.js?

Question

In node.js

> var name = 12; 
> console.log(typeof name);
number

in Firefox's web console

var name = 12; 
console.log(typeof name);
string 

let name2 = 12; 
console.log(typeof name2);
number 

Why is the difference between var and let in Firefox?

Why is no such difference in node.js?

Answer 1

There's an inbuilt property on window called name:

console.log(name);

So your code will look for that, not the name you create.