let function javascript code example

Example 1: javascript var let

// var has function scope.
// let has block scope.

function func(){
  if(true){
    var A = 1;
    let B = 2;
  }
  A++; // 2 --> ok, inside function scope
  B++; // B is not defined --> not ok, outside of block scope
  return A + B; // NaN --> B is not defined
}

Example 2: var vs let js

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

Example 3: const let var scope

var num = 1;   //var can be function or global scoped
const num = 2; //const can only be block scoped
let num = 3;   //let can only be block scoped

Example 4: 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

Example 5: let javascript

The let statement declares a block-scoped local variable, 
  optionally initializing it to a value.
let x=1;

Example 6: let javascript

var i = "global";
function foo() {
    var i = "local"; // Otra variable local solo para esta función
    console.log(i); // local
}
foo();
console.log(i); // global