es6☞对象的解构赋值

变量必须与属性同名

    let {name, age} = {name: 'wang', age: 22};
    console.log(name, age); //wang 22

    let {name} = {name: 'wang', age: 22};
    console.log(name); //wang

    let {sex} = {name: 'wang', age: 22};
    console.log(sex); //undefined

真正被赋值的是后者，而不是前者

    let {name: n,age: a} = {name: 'wang', age: 22};
    console.log(n,a) //wang 22

嵌套

    let people = {
        msg : [
            'Tom',
            {family: ['son', 'daughter', 'wife']}
        ]
    }
    let { msg:[x,{ family }] } = people;
    console.log(x,family)     //Tom  Array(2) ["son", "daughter", "wife"]

对象的解构赋值可以取到继承的属性

    const tom = {};
    const father = { height: 180};
    Object.setPrototypeOf(tom, father);

    const  { height } = tom;
    console.log(height); //180

指定默认值

    let {x, y = 5} = {x: 1};
    console.log(y); //5

    // 默认值生效的条件是，对象的属性值严格等于undefined。
    var {x = 3} = {x: undefined};
    console.log(x); // 3
    var {x = 3} = {x: null};
    console.log(x); // null