javacript中function (res) {}与箭头函数表达式(res) =＞{}的区别

javacript中function (res) {}与(res) =＞{}的区别

function (res) {} 代码演示

let shape = {name:'长方形',say:function(){console.log('我是'+this.name)setTimeout(function(){console.log('3秒后输出我是: ' + this.name);  //this.name为undefined}, 3000)}
}shape.say()

箭头函数表达式（lambda表达式），(res) =＞{}

lambda表达式 ()=>{something}或()=>something 相当于js中的函数,它的好处是可以自动将函数中的this附加到上下文中

将上面的function(){} 改成 ()=>{}

let shape = {name:'长方形',say:function(){console.log('我是'+this.name)setTimeout( ()=>{console.log('3秒后输出我是: ' + this.name);  //this.name可以正常输出}, 3000)}
}shape.say()

两者的区别