ES6_函数优化

function add(a , b) {
   // 判断b是否为空，为空就给默认值1
   b = b || 1;
   return a + b;
}
// 传一个参数
console.log(add(10));

function add(a , b = 1) {
    return a + b;
}
// 传一个参数
console.log(add(10));

var print = function (obj) {
    console.log(obj);
}
// 简写为：
var print2 = obj => console.log(obj);

// 两个参数的情况：
var sum = function (a , b) {
    return a + b;
}
// 简写为：
var sum2 = (a,b) => a+b;

var sum3 = (a,b) => {
    return a + b;
}

let person = {
    name: "jack",
    // 以前：
    eat: function (food) {
        console.log(this.name + "在吃" + food);
    },
    // 箭头函数版：
    eat2: food => console.log(person.name + "在吃" + food),// 这里拿不到this
    // 简写版：
    eat3(food){
        console.log(this.name + "在吃" + food);
    }
}

const person = {
    name:"jack",
    age:21,
    language: [‘java‘,‘js‘,‘css‘]
}

function hello(person) {
    console.log("hello," + person.name)
}

var hi = ({name}) =>  console.log("hello," + name);