看起来你在找“混合”它们不是内置在JavaScript中的，但在用户环境中很容易实现，例如：

function augment(cls, ...mixins) {
    return class extends cls {
        constructor(...args) {
            super(...args)

            for (let c of mixins)
                for (let p of Object.getOwnPropertyNames(c.prototype))
                    if (p !== 'constructor')
                        this[p] = c.prototype[p]
        }
    }
}

//

class Apple {}

class PhysicalObject {
    isFresh() {
        return 'hey'
    }
}

let AppleWithObject = augment(Apple, PhysicalObject)
let x = new AppleWithObject()
console.log(x.isFresh())

您只需要一个extends就可以实现您的结果。

class PhysicalObject {
   constructor(x,y) {this.x=x;this.y=y;}
   getPosition() {return {x:this.x,y:this.y}}
   displayPosition() {console.log(this.getPosition().x+', '+this.getPosition().y)}
   }
   
Earth=new PhysicalObject(0,0);
Earth.displayPosition();

class Fruit extends PhysicalObject {
  constructor(x,y,a) {super(x,y);this.age=a;}
  isFresh() {return this.age<7}
  }
  
Apple=new Fruit(1,1,6);
Apple.displayPosition();
console.log(Apple.isFresh());

关于被广泛误解的风险：受Douglas Crockford的启发，我停止使用类或原型（好吧，我在ES中从未使用过的类，never had any use for it）。
创建factory functions。这是一个示范性的水果工厂。
为了实现这个想法，我创建了一个小的Stackblitz project，使用了一种更通用的方法。

const FruitStore = FruitFactory();

FruitStore.apple = { 
  mustPeal: false, color: `red`, fresh: "Nope", origin: `Guatamala`, 
  inheritsFrom: {
    ...PhysicalObjectFactory(true), 
    ...ChemicalObjectFactory(true, null, true) },
};
FruitStore.orange = { inheritsFrom: {
  origin: `Spain`, fresh: false, color: `orange` } 
};
FruitStore.pineapple = { color: `yellow`, spherical: false, qty: `200Kg` };
console.log(FruitStore.all);
FruitStore.orange.fresh = `UNKNOWN`;
console.log(FruitStore.orange);

function PhysicalObjectFactory(spherical) {
  return { isPhysical: true, isSpherical: spherical };
}

function ChemicalObjectFactory(
  carbonBased = null, boilingPoint = null, solid = null) {
  return { carbonBased, boilingPoint, solid };
}

function FruitFactory() {
  let allFruits = {};
  // all fruits 'inherit' these properties
  // you can override any of them on
  // creating a fruit instance
  const fruitDefaults = {
    mustPeel: true,
    fresh: true,
    qty: `unset`,
  };
  const instance = { get all() { return allFruits; }, };
  // the proxy ensures you're working on the `allFruits` instance
  const proxy = { 
    get (obj, key) { return allFruits[key] ?? obj[key]; },
    set(_, key, props) { 
      allFruits[key] = createFruitInstance(key, props); 
      return true; 
    },
  };
  
  return new Proxy(instance, proxy);
  
  function createFruitInstance(name, props = {}) {
    const fruit = { name };
    let inherits = {};
    let inheritsFrom = { ...props.inheritsFrom };
    delete props.inheritsFrom;
    Object.entries({...fruitDefaults, ...props, ...inheritsFrom})
    .forEach( ([key, value]) => 
      value || key in fruitDefaults ? fruit[key] = value : false 
    );
    return fruit;
  }
}

.as-console-wrapper {
    max-height: 100% !important;
}