JavaScript/object.js at master · sill214/JavaScript · GitHub

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'use strict';

// Object
// 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
constobj1={};// 'object literal syntax
constobj2=newObject();// 'object constructor' syntax

functionprint(person){
console.log(person.name);
console.log(person.age);
}

constsill={name: 'sill',age: 20};
print(sill);

sill.hasJob=true;
console.log(sill.hasJob);

deletesill.hasJob;
console.log(sill.hasJob);

// 2. Computed properties
// key should be always string
console.log(sill.name);
console.log(sill['name']);
sill['hasJob']=true;
console.log(sill.hasJob);

functionprintValues(obj,key){
// console.log(obj.key); // Error
console.log(obj[key]);
}
printValues(sill,'name');

// 3. Property value shorthand
constperson1={name: 'bob',age: 2};
constperson2={name: 'steve',age: 3};
constperson3={name: 'dave',age: 4};
// const person4 = makePerson('sill', 20);
constperson4=newPerson('sill',20);
console.log(person4);

// 4. Constructor Funciton
functionPerson(name,age){
// return {
// name, // name: name
// age, // age: age
// };

// this = {};
this.name=name;
this.age=age;
// return this;
}

// 5. in operator: Property exsitence check(key in obj)
console.log('name'insill);
console.log('age'insill);
console.log('random',sill);
// console.log(sill.random) // undefined

// 6. for..in vs for..of
// for (key in obj)
console.clear();// 이전 console.log 가 지워짐
for(letkeyinsill){
console.log(key);
}

// for (value of interable)
constarray=[1,2,4,5];
// for(let i = 0; i < array.length; i++) {
// console.log(array[i]);
// }
for(letvalueofarray){
console.log(value);
}

// 7. Fun cloning
// Object.assign(dest, [obj1, obj2, obj3...])
constuser={name: 'sill',age: 20};
constuser2=user;
// user2.name = 'coder';
console.log(user);

// old way
constuser3={};
for(letkeyinuser){
user3[key]=user[key];
}
console.clear();
console.log(user3);

constuser4=Object.assign({},user);
console.log(user4);