数组对象解构赋值

对象

let node = {
  type: 'Identifier',
  name: 'foo'
};
let { type, name } = node;
console.log(type, name); // Identifier foo

let node = {
  type: 'Identifier'
};
let { type, name = 'wozien' } = node;
console.log(type, name); // Identifier wozien

let node = {
  type: 'Identifier',
  name: 'foo'
};
let { type: myType, name: myName = 'wozien' } = node;
console.log(myType, myName); // Identifier foo

数组

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let colors = ['red', 'green', 'blue'];
let [firstColor, secondColor] = colors;
console.log(firstColor, secondColor); // red green

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let colors = ['red'];
let [firstColor, secondColor = 'green'] = colors;
console.log(firstColor, secondColor); //red green

let colors = ['red', 'green', 'blue'];
let [firstColor, ...secondColor] = colors;
console.log(firstColor); //red 
console.log(secondColor); // [ 'green', 'blue' ]

应用场景

函数解构

function setCookie(name, value, { path, domain, expire }) {
  // 设置cookie
  console.log(path, domain);   // /，localhost
}
setCookie('a', 'b', { path: '/', domain: 'localhost' });

function setCookie(name, value, { path, domain, expire } = {}) {
  // 设置cookie
  console.log(path, domain);   // undefinded,undefinded
}
setCookie('a', 'b');