解构赋值let arr = [1, 2, 3, [4, 5]] let a = arr[0] let b = arr[1] let c = arr[2] console.log(a, b, c) let[a, b, c, d, e = 5] = arr //这是一个惰性赋值，如果传递的有值就是传入的值，没有就是默认值
console.log(a, b, c, d, e) console.log(...arr) let user = {
name: "Yangang",
age: 19
}
let name = user.name;
let age = user.age;
console.log(name, age) let {
name,
age
} = user let {
name: UserName,
age
} = user console.log(UserName, age) //这里面是经过键值对应可以换顺序
let str = "yan"let[a, b, c] = str console.log(a, b, c) console.log(...str) let {
name,
age = 18
} = {
name: "Yan",
age: 21
}
console.log(name, age) //Yan 21
function foo() {
console.log(123)
}
let[a = foo()] = []
function foo([a, b, c]) {
console.log(a, b, c)
}
let arr = [1, 2, 3] foo(arr) // 1 2 3
function foo({
name,
age,
school = "四川师范大学"
}) {
console.log(name, age, school)
}
let obj = {
name: "严钢",
age: 34,
school: "北京大学"
}
foo(obj) function foo() {
let obj = {
name: "严钢",
age: 34,
school: "北京大学"
}
return obj
}
let {
name,
age
} = foo() console.log(name, age)
let json = '{"a":"yangang","b":"一起设计吧"}'
let {
a,
b
} = JSON.parse(json) console.log(a, b) //yangang 一起设计吧
一起设计吧
