我想声明类中对象的值，并且仅在Im声明新类时调用键。我该怎么办？

Question

这就是我到目前为止所做的。class PriceCalc {  constructor(Obj) {    this.parts = Object.keys(Obj);    this.cost =      "$" +      Object.values(Obj)        .reduce((a, b) => a + b, 0)        .toFixed(2);    this.retail =      "$" +      (        Object.values(Obj).reduce((a, b) => a + b, 0) +        Object.values(Obj).reduce((a, b) => a + b, 0) * 1.75      ).toFixed(2);    this.quote = qt + this.retail;  }}var total = new PriceCalc({  Motherboard: 520.99,  RAM: 250.4,  SSD: 500.8,  HDD: 400.66,  Case: 375.5,  Monitor: 600.75,  Keyboard: 100.99,  Mouse: 25.5});console.log(total.parts);console.log(total.cost);console.log(total.retail);console.log(total.quote);Id想要实现的是将值声明在类中，然后只调用类似的东西var total = new PriceCalc({Motherboard, RAM, SSD, HDD});并返回指定部件的组合值，在本例中为 $1，672.85，对于此.cost

Answer 1

1. 将默认值放入类属性。

2. 传递要获取的属性字符串。

3. 用于获取对象属性this[b]

4. 确保你把数字而不是字符串相加：会给你字符串串联而不是算术运算。qt + this.quote

class PriceCalc {

  Motherboard = 520.99;

  RAM = 250.40;

  SSD = 500.80;

  HDD = 400.66;

  Case = 375.50;

  Monitor = 600.75;

  Keyboard = 100.99;

  Mouse = 25.50;

  

  parts = []

  cost = '$0'

  retail = '$0'

  quote = '0'

  constructor(Obj) {

    this.parts = Obj.join(',');

    this.cost = "$" + (Obj.reduce((a, b) => a + this[b], 0).toFixed(2));

    this.retail = "$" + ((Obj.reduce((a, b) => a + this[b], 0) + (Obj.reduce((a, b) => a + this[b], 0) * 1.75)).toFixed(2));

    //this.quote = qt + this.retail;

  }

}

var total = new PriceCalc([

  'Motherboard',

  'RAM',

  'SSD',

  'HDD'

]);

console.log(total.parts)

console.log(total.cost)

console.log(total.retail)

console.log(total.quote)