var let const - function

function foo() {
  // All variables are accessible within functions.
  var bar = 'bar';
  let baz = 'baz';
  const qux = 'qux';

  console.log(bar); 
  console.log(baz);
  console.log(qux); 
}

console.log(bar); 
console.log(baz); 
console.log(qux); 

var let const - if statement

if (true) {
  var bar = 'bar';
  let baz = 'baz';
  const qux = 'qux';
}

console.log(bar); 
console.log(baz); 
console.log(qux);