试图用JavaScript在HTML页面上显示段落。

Question

我的JavaScript遇到了一个问题。我试图将显示手机用户偏好的操作结果返回给用户。当我在Web浏览器中测试这段代码时，我在JavaScript控制台中显示一个空白的网页，没有任何错误。我是不是在这里做错了什么？下面显示的是我的代码。

// This is an array of the objects in the website, showing the phone information that will be used to filter for the user to view. 

const phones = [{
  name: "iPhone XS", brand: "Apple", cost: 43, data: "500MB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "iPhone 11", brand: "Apple", cost: 64, data: "90GB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "Galaxy S10", brand: "Samsung", cost: 30, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "Galaxy S10", brand: "Samsung", cost: 65, data: "Unlimited", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "Galaxy A10", brand: "Samsung", cost: 11.99, data: "500MB", minutes: 250, texts: "Unlimited"
},
{
  name: "Galaxy S9", brand: "Samsung", cost: 31, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "StarTAC 130", brand: "Motorola", cost: 3, data: "0MB", minutes: 200, texts: 500
},
{
  name: "Pixel 3A", brand: "Google", cost: 23, data: "4GB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "Xperia 10", brand: "Sony", cost: 30, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
},
{
  name: "P30", brand: "Huawei", cost: 27.99, data: "500MB", minutes: 500, texts: "Unlimited"
}]

// These are asking the user for entry of the data into the system.
const phoneBrand = prompt("Enter a phone brand")

const phoneCost = prompt("Enter a monthly cost")

const phoneData = prompt("Enter the amount of data")

const phoneMins = prompt("How many minutes?")

const phoneTexts = prompt("How many texts?")

// This is then filtering the object of phones to match what the user has entered into the system.

const matchingPhones = phones.filter(function(phone) {
    if(phone.brand===phoneBrand && phone.cost.toString()===phoneCost && phone.data===phoneData && phone.minutes.toString()===phoneMins && phone.texts.toString()===phoneTexts) {
        return true;
    }
    return false;

})

// This is then displaying data in the system.

const returnPhones = document.querySelector("#returnPhones");

matchingPhones.forEach(function(phone) {

    const newParagraph = document.createElement("p");
    newParagraph.textContent=`The matching plans are as follows - ${matchingPhones}`;
    returnPhones.appendChild(newParagraph);

})

Answer 1

我没有得到这个响应，＃1确保你定义returnPhones div之前的Javascript定义。

<div id="returnPhones">

</div>

我已经测试了下面的修改代码，它的工作。

    const phones = [{
    name: "iPhone XS", brand: "Apple", cost: 43, data: "500MB", minutes: "Unlimited", texts: "Unlimited"
},
    {
        name: "iPhone 11", brand: "Apple", cost: 64, data: "90GB", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "Galaxy S10", brand: "Samsung", cost: 30, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "Galaxy S10", brand: "Samsung", cost: 65, data: "Unlimited", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "Galaxy A10", brand: "Samsung", cost: 11.99, data: "500MB", minutes: 250, texts: "Unlimited"
    },
    {
        name: "Galaxy S9", brand: "Samsung", cost: 31, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "StarTAC 130", brand: "Motorola", cost: 3, data: "0MB", minutes: 200, texts: 500
    },
    {
        name: "Pixel 3A", brand: "Google", cost: 23, data: "4GB", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "Xperia 10", brand: "Sony", cost: 30, data: "20GB", minutes: "Unlimited", texts: "Unlimited"
    },
    {
        name: "P30", brand: "Huawei", cost: 27.99, data: "500MB", minutes: 500, texts: "Unlimited"
    }]

// These are asking the user for entry of the data into the system.
const phoneBrand = prompt("Enter a phone brand")

const phoneCost = prompt("Enter a monthly cost")

const phoneData = prompt("Enter the amount of data")

const phoneMins = prompt("How many minutes?")

const phoneTexts = prompt("How many texts?")

// This is then filtering the object of phones to match what the user has entered into the system.

const matchingPhones = phones.filter(function(phone) {
    if(phone.brand===phoneBrand && phone.cost.toString()===phoneCost && phone.data===phoneData && phone.minutes.toString()===phoneMins && phone.texts.toString()===phoneTexts) {
        return true;
    }
    return false;

})

// This is then displaying data in the system.

const returnPhones = document.querySelector("#returnPhones");

matchingPhones.forEach(function(phone) {

    const newParagraph = document.createElement("p");
    newParagraph.textContent='The matching plans are as follows - ' + phone.name;
    returnPhones.appendChild(newParagraph);

})