动态实例化传递参数

Question

我遇到了从不同类动态生成对象实例的问题。所以我有一个服务器响应返回一个产品数组，这些产品的类型不同，这将根据要使用的实例化类以及传递给构造函数的参数而有所不同。

在下面的示例中，我有一个根class Product，它由class Food 和classFurniture 扩展，这些扩展类的参数不同，需要插入到它们的相对constructors() 中。

我正在使用产品属性product.metaType 来保存class 在实例化中使用的信息。

//root product class which all inherit from
class Product{
	constructor(price){
		this.price = price;
		this.quantity = null;
	}	
}
//food product class
class Food extends Product{
	constructor(price,exp){
		super(price);
		this.expiration = exp;
	}	
}
//furniture product class
class Furniture extends Product{
	constructor(price,dimensions){
		this.price = price;	
		this.dimensions = dimensions;	
	}	
}
class Chair extends Furniture{
	constructor(price,dimensions,type){
		super(price,dimensions);
		this.type = type;
	}
}
class Pizza extends Food{
	constructor(price,exp,type){
		super(price,exp);
		this.type = type;
	}
}
class Cookies extends Food{
	constructor(price,exp,type){
		super(price,exp);
		this.type = type;
	}
}
class IceCream extends Food{
	constructor(price,exp,type){
		super(price,exp);
		this.type = type;
	}
}
//init (iife)
(()=>{	
	//list of products emulated from a server response
	var products:[
		{
			metaType: "Pizza",
			name: "digiorno",
			price: 20,
			type: "pepperoni",
			exp: new Date()
		},
		{
			metaType: "Chair",
			name: "Lazy Boy",
			price: 400,
		    dimensions:{
			   height: 4,
			   width: 2,
			  length: 6
		    },
			type: "modern"
		},
		{
			metaType: "Cookies",
			name: "Mrs. Fields",
			price: 10,
			type: "chocolate chip",
			exp: new Date()
		},
		{
			metaType: "IceCream",
			name: "Ben & Jerry's",
			price: 15,
			type: "half baked",
			exp: new Date()
		}
	];	
	var storeProducts = [];
	//loop through products array
	products.forEach((item)=>{
		//create new instance of the specific product, append to the 'storeProducts' array
		//each product contains a metaType property which is the CLASS to use
        //how can I dynamically do this?
		storeProducts.push(new window[item.metaType]());
	});
})();

问题：如何动态实例化不同的类并传递参数？

Answer 1

创建一个name -> constructor 映射。 classes 不会成为全局对象的属性：

const cls = {Food, Furniture, ...};

使构造函数接受单个参数并对其进行解构，例如

class Food extends Product{
  constructor({price,exp}){
      //      ^         ^    destructuring
      super(price);
      this.expiration = exp;
  } 
}

然后你可以将整个对象传递给构造函数：

 new cls[item.metaType](item);