構造分解の割り当て

💡 定義＃テイギ＃

💡 ぶんかいアレイこうぞう

let users = ['Mike', 'Tom', 'Jane'];
let [user1, user2, user3] = users;

let [user1, user2, user3]

let user1 = users[0];
let user2 = users[1];
let user3 = users[2];

console.log(user1); // 'Mike'
console.log(user2); // 'Tom'
console.log(user3); // 'Jane'

let str = "Mike-Tom-Jane";
let [user1, user2, user3] = str.split('-');

str.split('-');

['Mike', 'Tom', 'Jane']

console.log(user1); // 'Mike'
console.log(user2); // 'Tom'
console.log(user3); // 'Jane'

let [a, b, c] = [1, 2];
console.log(c); // undefind

let [a=2, b=3, c=4] = [1, 2];
console.log(a); // 1
console.log(b); // 2
console.log(c); // 4

let [user1, ,user2] = ['Mike', 'Tom', 'Jane', 'Tony'];
console.log(user1); // 'Mike'
console.log(user2); // 'Jane'

let a = 1;
let b = 2;

let a = 1;
let b = 2;

let c = a; // 임시 변수
a = b;
b = c;

[a, b] = [b, a];

💡 オブジェクト構造の分解

let user = {name: 'Mike', age: 30};
let {name, age} = user;

console.log(name); // 'Mike'
console.log(age); // 30

let {name, age} = user;

let name = user.name;
let age = user.age;

let {age, name} = user;

let user = {name: 'Mike', age: 30};
//let {name, age} = user;
let {name: userName, age: userAge} = user;

console.log(userName); // 'Mike'
console.log(userAge); // 30

let user = {name: 'Mike', age: 30};
let {name, age, gender} = user;

console.log(gender); // undefined

let user = {
  name: 'Jane',
  age: 18,
  gender: 'female'
}

let {name, age, gender='male'} = user;

console.log(gender); // 'female'