ES6学习笔记2--解构赋值

解构赋值

用字面量的方法将对象或数组中的值赋给变量

解构

对数组解构

var [a, [b], c] = [1, [2], 3]; //a = 1; b = 2; c = 3;// 注意这里的b,数组嵌套也是可以正常解构的

对基本类型、undefined、null解构

var [a, b] = 12; // 报错：undefined is not a functionvar [c] = false; // 抱错：undefined is not a functionvar [d] = '12'; // d = 1;var [e] = undefined; // 报错：Cannot read property 'Symbol(Symbol.iterator)' of undefinedvar [f] = null // 报错：Cannot read property 'Symbol(Symbol.iterator)' of null

对对象解构

var {a, b} = {b: 1, a: 2}; // a = 2; b = 1;var {a: c, b: d} = {b: 1, a: 2} // d = 1; c = 2;var {a} = {b: 1}; // a = undefined

默认值

只有在解构的值严格等于undefined的情况下解构才使用默认值，对象解构同理

var [a = 1] = []; //a = 1;var [a = 1] = [undefined]; //a = 1;var [a = 1] = [null] // a = null;