當(dāng)ES6 Arrow函數(shù)似乎無法使用prototype.object將函數(shù)分配給對象時?？紤]以下示例：function Animal(name, type){ this.name = name;  this.type = type;  this.toString = () => `${this.name} is a ${this.type}`;}var myDog = new Animal('Max', 'Dog');console.log(myDog.toString()); //Max is a Dog在對象定義中顯式使用arrow函數(shù)是可行的，但將Object函數(shù)與Object.prototype語法一起使用不能：function Animal2(name, type){  this.name = name;  this.type = type;}Animal2.prototype.toString = () => `${this.name} is a ${this.type}`;var myPet2 = new Animal2('Noah', 'cat');console.log(myPet2.toString()); //is a undefined就像概念證明一樣，將Template字符串語法與Object.prototype語法結(jié)合使用確實可以：function Animal3(name, type){  this.name = name;  this.type = type;}Animal3.prototype.toString = function(){ return `${this.name} is a ${this.type}`;}var myPet3 = new Animal3('Joey', 'Kangaroo');console.log(myPet3.toString()); //Joey is a Kangaroo我是否缺少明顯的東西？我覺得示例2應(yīng)該在邏輯上起作用，但是我對輸出感到困惑。我猜這是一個范圍界定的問題，但是輸出“是未定義的”讓我望而卻步。