text: // javascript에서는 주석은 //이렇게 처리한다. 
  
  //변수 선언
  let value = 1;
  const a = 1;
  
  //Actually in the past they used var
  var b = 1;
  var c = 2;
  
  // string 
  let text = 'There is something wrong with me';
  let name = "Wonjun Jang";
  
  // Boolean 
  let good = true;
  let bad = false;
  
  // null, undefined
  let theWorld = null;
  let Myfuture = undefined;
  
  let something  = 1;
  something++; // -> after the operation something + 1
  ++something;// -> before the operation something  + 1
  console.log(something);
  
  //논리연산자
  let value = true;
  value = false; 
  
  //JavaScript에서는 이렇게 만든다.
  //NOT AND OR
  // !  &&  ||
  //Priority = > NAO
  
  const a = !false;
  const b = true && true;
  const c = true || false;
  const d = !true;
  
  const value = !(true && false || true && false || !false);
  
  // 비교 연산자
  const a = 1;
  const b = 2;
  const equals = a === b;
  const notEquals = a !== b;
  console.log(equals,notEquals);
  
  // JS에서는 무조건 ===를 사용한다. !== 과 마찬가지로
  const a = "Hello";
  const b = 'Wolrd';
  
  //조건문
  const a = 1;
  if (a+1 === 2){
      console.log("a+1 is 2"+a);
  }
  console.log('The a outside is a'+a);
  
  //if-else if- else
  const name = "Jang Wonjun";
  if (name === 'Jang Wonjun'){
      console.log("It's you Wonjun!");
  }
  else if (name === 'Jang Wonseok'){
      console.log('Oh you again..');
  }
  else console.log('Who the hell are you?');
  
  //switch-case 
  
  const device = 'iphone';
  
  switch (device) {
      case 'iphone':
          console.log('iphone!');
          break;
      case 'ipad':
          console.log('ipad!');
          break;
      case 'applewatch':
          console.log('applewatch!');
          break;
      case 'galaxy note':
          console.log('Who would use SAMSUNG!');
          break;
      default:
          console.log('There is no default.');
  }
  
  //function
  function hello(name){
      console.log(`Hello ${name}`);
  }
  hello('Wonjun');
  hello('Wonseok');
  
  //화살표 함수
  const add = (a, b) => { return a + b;}
  const bye = (name) => { console.log(`Bye ${name}`); }
  const subtract = (a, b) => { return a - b; }
  const subtract2 = (a, b) => a - b;
  // so basically the things on the left side of the arrow
  //  is the variables and the thing on the right side of
  // the arrow is the return value
  
  //object
  const dog = {
      name: 'Sam',
      age: 2,
      cute: true,
      puppy: {
          son: Jim,
          daughter: Kelly,
      }
  };
  
  console.log(dog);
  console.log(dog.name);
  console.log(dog.age);
  
  // class