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ES6继承问题

class Father{
    say(){
        console.log('father')
    }

}
class Son extends Father{
    say(){
        console.log(super.say())
    }
}
let son = new Son();
son.say()
为什么打印出来第一个是father,会出现第二个是undefined

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class Son extends Father {
    say() {
        // 在这里,super 指向的是 Father 的原型对象
        // 相当于调用了 Father.prototype.say(),该方法中打印了 'father',但没有返回值,默认返回 undefined。所以在子类中打印 undefined。
        console.log(super.say());
    }
}

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