var-vs-let-function-scope.js

function myFuncVar() {
  // Declare a variable using var inside myFunc's funciton scope
  var x = 1;
  console.log(x);

  if (true) {
    // Since var is function scoped and not block scoped,
    // we are actually overwriting the value of the x variable
    var x = 2;
    console.log(x);
  }
  // Will print out 2 since we overwrote the variable in the if statement
  console.log(x);
}

function myFuncLet() {
  // Declare a variable using var inside myFunc's funciton scope
  let x = 1;
  console.log(x);

  if (true) {
    // Creating a new variable x = 2 inside the block scope
    // (this is not accessible outside of the if statement's curly braces)
    let x = 2;
    console.log(x);
  }
  // 1 since console.log() cannot access x = 2 variable defined
  // in the if statement due to block scope
  console.log(x);
}

// Call the functions
myFuncVar();
myFuncLet();