<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<script type="text/javascript">
//一个参数
const power = (num1) => {
return num1 * num1;
}
//一个参数可以省略括号：
const power1 = num1 => {
return num1 * num1
}
//多个参数
const add = (num1, num2) => {
return num1 + num2;
}
//当函数代码块中只有一行代码
const mul = (num1, num2) => num1 * num2;
const demo = () => console.log("hello vue.js")
console.log(mul(20, 30))
demo()
//问题：箭头函数中this是如何指向
//结论：向外层作用域中一层一层查找，直到有this的定义
const obj = {
aaa() {
setTimeout(function() {
console.log(this) //window
setTimeout(() => {
console.log(this) //window
})
})
setTimeout(() => {
console.log(this) //window
setTimeout(() => {
console.log(this) //obj
})
})
}
}
obj.aaa();
</script>
</body>
</html>
