object.js

// Objects
// one of the JavaScript's data types.
// a collection of related data and/or functionality.
// Nearly all objects in JavaScript are instances of Object
// object = { key : value };

// 1. Literals and properties
const obj1 = {}; // 'object literal' syntax
const obj2 = new Object(); // 'object constructor' syntax

function print(person) {
  console.log(person.name);
  console.log(person.age);
}

const och = { name: "och", age: 27 };
print(och);

// with JavaScript magic (dynamically typed language)
// can add properties later
// can delete properties later
och.hasJob = true;
console.log(och.hasJob);

// 2. Computed(계산된) properties
// key should be always string
console.log(och.name); // 값을 정확하게 알때
console.log(och["name"]); // runtime에서 결정될때

// 3. Property value shorthand
const person1 = { name: "bob", age: 2 };
const person2 = { name: "steve", age: 3 };
const person3 = { name: "dave", age: 4 };
const person4 = new Person("och", 27);
console.log(person4);

// 4. Constructor function
function Person(name, age) {
  // this = {};
  this.name = name;
  this.age = age;
  // return this;
}

// 5. in operator : property existence check ( key in obj )
console.log("name" in och);
console.log("age" in och);
console.log("random" in och);
console.log(och.random);

// 6. for.. in vs for.. of
// for (key in obj)
console.clear();
for (key in och) {
  console.log(key);
}

// for (value of iterable)
const array = [1, 2, 4, 5];
for (value of array) {
  console.log(value);
}

// 7. Fun cloning
// Object.assign(dest, [obj1, obj2, obj3...])
const user = { name: "och", age: 27 };
const user2 = user;
console.log(user);

// old way
const user3 = {};
for (key in user) {
  user3[key] = user[key];
}
console.clear();
console.log(user3);

// another way
const user4 = Object.assign({}, user);
console.log(user4);

// another example
const fruit1 = { color: "red" };
const fruit2 = { color: "blue", size: "big" };
const mixed = Object.assign({}, fruit1, fruit2);
console.log(mixed.color);
console.log(mixed.size);