這就是我到目前為止所做的。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想要實(shí)現(xiàn)的是將值聲明在類中，然后只調(diào)用類似的東西var total = new PriceCalc({Motherboard, RAM, SSD, HDD});并返回指定部件的組合值，在本例中為 $1，672.85，對(duì)于此.cost