解构赋值：按照一个数据值的结构，快速解析获取到其中的内容
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数组解构赋值
1.想要几个就几个
2.设置默认值也行（默认解构）let ary = [12, 23, 34, 45, 56]; let [a, b, c] = ary; console.log(a, b, c); // 12 23 34 let [d] = ary; console.log(d); // 12 // 省略赋值 let [e, , f] = ary; console.log(e,f); // 12 34
3.不仅可以解构成单个值，还可以返回个数组let ary = [12]; let [a, b = 0] = ary; console.log(a, b); // 12 0
4.互换位置更加方便let ary = [12, 23, 34, 45, 56]; let [a, ...b] = ary; console.log(a, b); // 12 [23,34,45,56] let [a, ...b, c] = ary; // SyntaxError: Rest element must be last elementlet a = 12, b = 13; [a, b] = [b, a]; console.log(a, b); // 13 12 -
对象解构赋值
1.对象解构赋值默认情况下要求：左侧变量名和对象中的属性名一致才可以
2.给不存在的属性设置默认值let obj = {name: 'xxx', age: 25, sex: 0}; let {name, age} = obj; console.log(name, age); // "xxx" 25
3.给解构的属性名起别名作为需要使用的变量let obj = {name: 'xxx', age: 25, sex: 0}; let {friend = 0} = obj; console.log(friend); // 0let obj = {name: 'xxx', age: 25, sex: 0}; let {age: ageAA} = obj; console.log(age); // Uncaught ReferenceError: age is not defined console.log(ageAA); // 25
