const who = 'World'

// Declaring a function
function sayHi () {
  const greeting = 'Hi'
  document.write(`${greeting}, ${who}. <br><br>`)
}

// Calling the function
sayHi()

// Checking the value of greeting
if (typeof greeting === 'undefined') {
  document.write(`The variable <code>greeting</code> is not defined.`)
}