案例代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>函数扩展</title>
</head>
<body>
<script type="text/javascript" src="js/jquery.js" ></script>
<script>
//1.形参设置默认值
function sum(sum1=10,sum2=10){
console.log(sum1+sum2);
}
sum(1,3);
sum();
//2.参数形式 延展操作符
//ES5
function summ(){
let re=0;
for(let value of arguments){
re+=value;
}
return re;
}
console.log(summ(10,60));
//ES6
function summm(name,...nums){
let re=0;
console.log(name);
for(let value of nums){
re+=value;
}
return re;
}
console.log(summm('大金',10,80));
//3.箭头函数
let s=(num1,num2) => {return num1+num2;};
console.log(s(100,200));
let nameArr=['小明','小红','小兰'];
nameArr.forEach((value,index)=>{
console.log(index+':'+value);
});
//解决this绑定问题
function demo(){
//window对象
setTimeout(function(){
console.log(this);
},1000);
//调用该函数的对象
setTimeout(()=>{
console.log(this);
},1000);
}
let obj={};
demo.call(obj);
</script>
</body>
</html>