ES6对象解构赋值详解：语法、嵌套、默认值与常见错误处理

var {name} = {
 name:'Joh',
 age:10
};
console.log(name); // Joh

var {name} = {
 name:'Joh',
 age:10
};
console.log(name); // Joh

// 通过{属性：新的名称} = 对象的方式 对解构出的属性进行重命名
var {color:color2} = {
 color:'red',
 age:10
};
console.log(color2); // red
console.log(color); // 此处报错：Uncaught ReferenceError: color is not defined

var obj = {
   a:{
    b:{
     c:123
    }
   }
};
let {a:{b:{c}}} = obj; // 针对嵌套解构的最终输出只能是最里层的，外层的a和b都作为解构中的一种模式存在，而不是变量，只有c能正常输出
console.log(c); // 123
console.log(a, b, c); // Uncaught ReferenceError: a is not defined 报错之后停止

var obj = {
 name:'Joh',
 age:22
};
var {name, id='999', age} = obj;
console.log(name, id ,age); // Joh 999 22

var obj2 ={
 name:'Lily',
 age:10
};
var {name:name2, id:id2='888', age:age2} = obj2;
console.log(name2, id2, age2); // Lily 888 10

let {x:{y}} = {name:{y:12}};
// 父结构中没有x属性名, 错误：Cannot destructure property `y` of 'undefined' or 'null'.

let name;
let {name} = {name:'Joh'};
// Uncaught SyntaxError: Identifier 'name' has already been declared

let name;
let {name:name2} = {name:'Joh'};
console.log(name2);
//运行结果：Joh

var name;
var {name} = {name:'Joh'};
console.log(name);
//运行结果：Joh