写法

// 只有一个参数
var f = a => a;
var f = function(a) {
	return a;
};

var f = () => 1;
function f() {
	return 1;
}

let f = (a, b) => {
	return a + b;
};

const full = ({first, last} = {}) => first + ' ' + last;
console.log(full({first: 3, last: 5})); // 35

var arr = [123,4,55,6,7,67,4,56,34,3,54,666,3,7];
var arr1 = arr.sort((a, b) => a - b);
console.log(arr1);

⭐️ 箭头函数是匿名函数，不能作为构造函数 new

var B = () => {
  value:1;
}
var b = new B();  //-->TypeError: B is not a constructor

⭐️ 箭头函数中没有 arguments 对象

var sum = (a, b) => {
	console.log(arguments);
  return a + b;
}
sum(1, 3);

... spread/rest 运算符（展开或收集）

收集

var sum = (...args) => {
	console.log(args);
  console.log(args[0] + args[1]);
}
sum(1, 2);

⭐️ rest 收集，必须是最后一个参数

let fn = (a, b, ...c) => {
	console.log(a, b, c);
}
fn(1, 2, 3, 4, 5);

展开

function foo(x, y, z) {
	console.log(x, y, z);
}
foo(...[1, 2, 3]);