rest parameter 和 Destructuring assignment.

function fun1(...theArgs) {

console.log(theArgs.length);

}

// theArgs is an array

fun1(); // 0

fun1(5); // 1

fun1(5, 6, 7); // 3

function f(a, b, ...theArgs) {

// ...

}

function f(...[a, b, c]) {

return a + b + c;

}

f(1) // NaN (b and c are undefined)

f(1, 2, 3) // 6

f(1, 2, 3, 4) // 6 (the fourth parameter is not destructured)

见 ECMAScript 6 (2015)

Arrow function

* 简洁的语法，

* 没有自己的this， arguments， super 和 new.target.

特别适用于非属性函数，

不能用作构造函数.

function Person(){

this.age = 0;

setInterval(() => {

this.age++; // |this| properly refers to the person object

}, 1000);

}

var p = new Person();