傳統的賦值方式

let x = 1;
let y = 2;
let z = 3;
//或
let x = 1,
    y = 2,
    z = 3;

ES6中採用陣列模式   運算子

let [x,y,z] = [1,2,3];

let arr = [1,2,3];
let [a,b,c] = arr;

模式匹配,一一對應

let [a,,c] = [1,2,3];      //a = 1; c = 3;
let [a,b,c] = [1,2];        //c = undefined

帶預設值

let [a = 1] = ['a']; // a = 'a';
let [a = 1] = [];    // a = 1;
 

需要特別注意，如果解構的值為undefined，則取預設值

let [b = 1] = [undefined];  //1
let [b = 1] = [null];       //null

解構的物件不僅僅可以是單一的值，也可以是物件或陣列

let [a,b,c] = [1,[2,3],4];
let [a,b,c] = [1,{x:'x'},4];

在物件的結構中，如下例，name是匹配模式，a才是變數

let {name:a,age:b} = {age:20,name:'abc'};  //a = 'abc';b = 20;
let {name,age} = {age:20,name:'abc'};  //相當於let {name:name,age:age} = {age:20,name:'abc'}
let {abc:name,age:age} = {age:20,name:'abc'};   //錯誤  name為變數， abc是物件中匹配的值