when should we use let in function in javascript code example

Example 1: var vs let js

let: //only available inside the scope it's declared, like in "for" loop, 
var: //accessed outside the loop "for"

Example 2: let in javascript

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

let x = 1;

if (x === 1) {
  let x = 2;

  console.log(x);
  // expected output: 2
}

console.log(x);
// expected output: 1