<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
//对象的解构赋值:
let obj = {
a: 1,
b: 2,
c: 3
}
let {
b,
c
} = obj; //对象的解构赋值,按照属性名解构, 不受顺序影响
// 可以不用let,但一般会加let
//a,b,c可以换顺序==>b,a,c
let a = 666;
let {
a: qq, //这是起别名, 不能看作是对象的键值对
} = obj;
console.log(qq); // 1
let obj2 = {
a: 1,
b: 2,
c: 3,
d: 4,
}
let {
aa,
bb,
...t //只能用在最后
} = obj2;
console.log(t); // { a: 1, b: 2, c: 3, d: 4 }
//数组的解构赋值(会受顺序影响):
let arr = [11, 22, 33, 44, 55, 66];
let [, k] = arr; //数组的解构是以位置(索引)为基准;
console.log(k); //22
let x = 2,
y = 3;
[y, x] = [x, y]; //这样就很简单的把x和y的位置交换了;
[i, o] = [x, y];
console.log(x, y); // 3 2
console.log(i, o); // 3 2
function fn1(arr = []) { // es6的形参赋值
console.log(arr.length); //这样会是undefined.length会报错
}
fn1 && fn1(); //fn1存在 才有 fn1执行
//解构赋值实现浅拷贝:
let arr1 = [111, {
q: 232
}];
let [...ttt] = arr1;
console.log(ttt);
ttt[1].q = 123; //那么arr1的q也会改变为123, 因为{q:232}是公有的堆地址
ttt[1].a = 111; //不会改变arr1,因为ttt是私有的地址
</script>
</body>
</html>
