我应该在子类中使用super（）调用父类方法

Posted 2021-04-29

我在javascript中有关于super（）的问题。我应该在子类中使用super（）调用父类方法'stringy（）'还是这样使用它：

function solve() {
class Melon {
    constructor(weight, melonSort) {
        if (new.target === Melon) {
            throw new Error('Abstract class cannot be instantiated directly.')
        }
        this.weight = weight;
        this.melonSort = melonSort;
        this._elementIndex = weight * Number(melonSort.length);

    }
    stringy() {
        return `Element: ${this.element}
Sort: ${this.melonSort}
Element Index: ${this._elementIndex}`
    }
}

class Watermelon extends Melon {
    constructor(weight, melonSort) {
        super(weight, melonSort);
        this.element = 'Water';
    }
}

或

function solve() {
class Melon {
    constructor(weight, melonSort) {
        if (new.target === Melon) {
            throw new Error('Abstract class cannot be instantiated directly.')
        }
        this.weight = weight;
        this.melonSort = melonSort;
        this._elementIndex = weight * Number(melonSort.length);

    }
    stringy() {
        return `Element: ${this.element}
Sort: ${this.melonSort}
Element Index: ${this._elementIndex}`
    }
}

class Watermelon extends Melon {
    constructor(weight, melonSort) {
        super(weight, melonSort);
        this.element = 'Water';
    }

    stringy(){
        return super.stringy();
    }
}

哪个是正确的，和有什么区别。

答案

除非您要更改行为，否则无需在stringy中包含Watermelon。如果您不这样做，Watermelon实例将继承Melon版本。