如何使用 javascript object function 返回一个值并将其用作 object 属性。？

Question

In selling price I expect to get 1000-20% ie 800 by passing MRP and discount as arguments to the function get_selling_price, but my code gives error get_selling_price undefined get_selling_price. Please help me to fix it and let me know why this happened, since I declared the function before using it.

let Sock = {
    brand: 'JS',
    color: 'Red',
    size: "extra-extra small",
    MRP: 1000,
    discount: 20,
    
    get_selling_price: (MRP, discount)=>{return MRP-((MRP*discount)/100)},
    selling_price: get_selling_price(this.MRP, this.discount),

    buy: ()=>console.log(`You are buying ${this.brand}`),
    sell: function(){console.log(`You are selling ${this.brand}`)},

}

console.log(Sock);

Answer 1

In JavaScript, if you want to access the information stored inside the object from the object method, you need to use regular function() instead of arrow function . In your case, to access the get_selling_price function inside selling_price of the Sock object, you need to define selling_price as a regular function and access another function/property of the object using this keyword (see sample below).

let Sock = {
  brand: "JS",
  color: "Red",
  size: "extra-extra small",
  MRP: 1000,
  discount: 20,

  get_selling_price: (MRP, discount) => {
    return MRP - (MRP * discount) / 100;
  },
  selling_price: function () {
    return this.get_selling_price(this.MRP, this.discount);
  },

  buy: () => console.log(`You are buying ${this.brand}`),
  sell: function () {
    console.log(`You are selling ${this.brand}`);
  },
};

Also, just to mention, I recommend you get acknowledged with this keyword in JavaScript, you can refer to this documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this