vue常用的ES6语法--函数扩展

1、形参设置默认值

        /* function sum(num1,num2){
            num1 = num1 || 10;
            num2 = num1 || 10;
            console.log(num1+num2);
        } */
        function sum(num1=10,num2=10){
            console.log(num1+num2);
        }
        sum(20,30);
        

2、延展操作符

        function sum(name, sex, ...nums){
            let result = 0;
            console.log(name);
            console.log(sex);
            for(let value of nums){
                value += value;
            }
            return result;
        }

        console.log('bob','男',10,20,30);//bob 男 60

3、箭头函数

        let sum = (num1,num2) => {return num1 + num2;}

        //箭头函数不用担心this指向问题
        function demo(){
            setTimeout(function(){
                console.log(this);//指向window
            },3000);

            setTimeout(() => {
                console.log(this);//指向{}
            },3000);
        }

        let obj = {};
        demo.call(obj);