Javascript for loop in shows undefined

Question

MY JSON is:

[
    {
        "id": "5d7d855c-7301-4b2f-9676-3cb758316b4c",
        "products": [
            {
                "id": 1,
                "price": 699.0,
                "quantity": 2,
                "color": "silver",
                "size": "128GB"
            }
        ],
        "contact": {
            "name": "5423654",
            "surname": "gdfsgsdf",
            "address": "gfdsg",
            "phone": "53454353",
            "city": "5234532",
            "country": "gfdsgfds"
        },
        "shippingPrice": 0.0,
        "discount": null,
        "totalPrice": 1398.0
    }
]

I am trying to loop in it with for loop in


class Orders {
    _orders;

    constructor() {
        this.init().then(() => this.renderOrders());
    }

    async init() {
        this._orders = await this.getOrders();
    }

    GET(url) {
        try {
            return axios.get(url)
        } catch (e) {
            return e;
        }
    }

    getOrders() {
        return new Promise(resolve => {
            this.GET('http://localhost:8080/orders/getOrders').then(response => {
                resolve(response.data);
            })
        })
    }

 renderOrders() {
        const template = document.getElementById("orders__template");
        const container = document.getElementById("orders");
        container.innerHTML = "";

        console.log(typeof this._orders);

for (let key in this._orders) {
            if (this._orders.hasOwnProperty(key)) {

                for (let productKey in this._orders[key].products) {
                    if (this._orders[key].products.hasOwnProperty(productKey)) {
                        console.log(this._orders[key].products[productKey].id); //getting the id
                    }
                }

                for (let discountKey in this._orders[key].discount) {
                    if (this._orders[key].discount.hasOwnProperty(discountKey)) {
                        console.log(this._orders[key].discount[discountKey].id); //undefined(even when it's not null, why?
                    }
                }

                for (let contactKey in this._orders[key].contact) {
                    if (this._orders[key].contact.hasOwnProperty(contactKey)) {
                        console.log(this._orders[key].contact[contactKey].name); //undefined too
                    }
                }

            }

        }
}

document.addEventListener("DOMContentLoaded", () => {
    new Orders();
});

However, i am getting only at first for loop result, other discount, or contact are undefined. i tried with other dummy data, i am getting the same results, so, what is the problem? However, i have other examples where it do work, the same structure, whats wrong?

May you update the example to show a minimal reproducible example? At the moment it's not clear how to run the code to reproduce the error you see — evolutionxbox
– evolutionxbox, Commented Apr 23, 2021 at 14:31
Your products is an array of object whereas contact is an object. The last loop, loops over the properties (name, surname etc.), not over the array items. — Ivar
– Ivar, Commented Apr 23, 2021 at 14:37

vuongvu · Accepted Answer · 2021-04-23 14:43:57Z

1

in the orders object, property discount and contact are not arrays so you don't need to use for loop:

for (let key in order) {
  if (order.hasOwnProperty(key)) {
    for (let productKey in order[key].products) {
      if (order[key].products.hasOwnProperty(productKey)) {
        console.log(order[key].products[productKey].id); //getting the id
      }
    }

    if (order[key].discount) {
      console.log(order[key].discount.id);
    }

    if (order[key].contact) {
      console.log(order[key].contact.name);
    }
  }
}

answered Apr 23, 2021 at 14:43

vuongvu

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