ES6（一）解构赋值

变量

let num = 123
const str = '123'
console.log(num, str)



解构赋值

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

{
  let a, b, arr
  [a, b, ...arr] = [1, 2, 4, 5, 6, 7, 8, 9]
  // 1 2
  console.log(a, b)
  // [4, 5, 6, 7, 8, 9]
  console.log(arr)
}

{
  let a, b
  ({a, b} = {a: 1, b: 2})
  // 1  2
  console.log(a, b)
}

{
  let a = 1
  let b = 2;
  // 变量交换
  [a, b] = [b, a]
  console.log(a, b)
}
    



数组解构

test () {
  return [1, 2]
}
let a, b
[a, b] = this.test()
// 1  2
console.log(a, b)

只取需要的值

test () {
  return [1, 2, 3, 4, 5]
}
let a, b
[a, , , b] = this.test()
// 1  4
console.log(a, b)

let a, b
[a, ...b] = this.test()
// 1  [2, 3, 4, 5]
console.log(a, b)

let a, b
[a, , ...b] = this.test()
// 1  [3, 4, 5]
console.log(a, b)




对象解构

let a = {name: 'ronle', index: 1}
let {name, index} = a
// ronle  1
console.log(name, index)

let a = {user: 'ronle', num: 1}
// 变量重命名
let {user: name, num: index} = a
console.log(name, index)

let {a = 10, b = 5} = {a: 3}
// 3  5
console.log(a, b)

let metaDate = {
  title: 'hello',
  test: [
    {
      name: 'ronle',
      desc: 'desc'
    }
  ]
}
let {title: esTitle, test: [{name: cnName}]} = metaDate
// hello  ronle
console.log(esTitle, cnName)