functions.js

function myFunction() {
  // no arguments present
  console.log('Hellow World');
}

myfunction(); // shows Hello World in the console

function myFunction(message) {
  // one arguments present
  console.log(message);
}

myfunction('Hello World'); // shows Hello World in the console

function myFunction(message = 'Hello World') {
  // one arguments present
  console.log(message);
}

myfunction(); // shows Hello World in the console
myfunction('Hello Austin!'); // shows Hello Austin! in the console

function myFunction(message, time) {
  // two arguments present
  if (time == now) {
    console.log(message);
  } else {
    console.log('It is not time yet.');
  }
}

myfunction('Hello World', 'now'); // shows Hello World in the console
myfunction('Hello World', 'later'); // shows It is not time yet. in the console