let func = function(arg1, arg2, ..., argN) {
  return expression;
};

function sayHello() {
    console.log("Hello!");
}
sayHello(); // "Hello!"

const sayHello = function() {
    console.log("Hello!");
};
sayHello(); // "Hello!"

const sayHello = () => {
    console.log("Hello!");
};
sayHello(); // "Hello!"

const add = (a, b) => a + b;
console.log(add(2, 3)); // 5

function Person(name, age) {
    this.name = name;
    this.age = age;
}
const person1 = new Person("Ali", 25);
console.log(person1.name); // "Ali"

(function() {
    console.log("This runs immediately!");
})();

function* generator() {
    yield 1;
    yield 2;
    yield 3;
}
const gen = generator();
console.log(gen.next().value); // 1
console.log(gen.next().value); // 2

function ask(question, no, yes){
  if(confirm(question))yes()
  else no()
}
ask("do you agere?"
  function(){alert{"You agreed!"}; },
  function(){alert{"You canceled the execution!"}; }
);

let userName = prompt("Your name?", "Alice");
let isTeaWanted = confirm("Do you want some tea?");

alert( "Visitor: " + userName ); // Alice
alert( "Tea wanted: " + isTeaWanted ); // true

let isBoss = confirm("Are you the boss?");

alert( isBoss ); // true if OK is pressed