问题

我对JavaScript还很陌生，但对Java了解很多。我试图通过做一些小项目来学习基础知识，以便理解这门语言和代码。在Java中，我经常与将数据从映射存储在JSON文件中并在程序启动时将JSON文件加载到映射中进行交互。

以下是Java的示例：

```java
public Map<Integer, Client> example = new HashMap<>();

以下是Client类的定义：

public class Client {

    private String username;
    private String password;
    private String host;

    public Client(String username, String password, String host) {
        this.username = username;
        this.password = password;
        this.host = host;
    }

    public String getPassword() {
        return password;
    }

    public String getHost() {
        return host;
    }

    public String getUsername() {
        return username;
    }
}

我想要在JavaScript中做同样的事情。我的映射看起来像这样：

var price = new Map();

与上面的Java示例类似，我希望将这样的映射加载到一个JSON文件中，并从JSON文件中加载数据到我的映射中。

有人可以为我提供一个代码示例，演示如何将JSON中的数据存储到映射中吗？甚至提供一个教程链接也会很棒！

<details>
<summary>英文:</summary>

I&#180;m quite new to Javascript, but know a lot about Java. Im trying to learn the basics by doing little projects, for understanding the language and code. In Java, i worked a lot with storing data from maps in json-files and, when you start the programm, the json file loads the data into the map. 

An example for Java: 

    public Map&lt;Integer, Client&gt; example = new HashMap&lt;&gt;();
Herefor the Client class :

    public class Client {

    private String username;
    private String password;
    private String host;

    public Client(String username, String password, String host) {
        this.username = username;
        this.password = password;
        this.host = host;
    }

    public String getPassword() {
        return password;
    }

    public String getHost() {
        return host;
    }

    public String getUsername() {
        return username;
    }
    }

I want to do the same thing, but now in Javascript. My map looks like that:

    var price= new Map();

Like the Java example above, I want to load such a Map into a json file and want to load the data from the json file into my map.

Could somebody proivde me with a good example of code, how to store data from json in my map ? Even a link for a tutorial would be great!

</details>


# 答案1
**得分**: 2

在JS中，使用普通对象而不是`Map()`更为常见。
例如，假设您有相同的`Client`类：

```js
class Client {
    constructor(username, password, host) {
        this.username = username;
        this.password = password;
        this.host = host;
    }
}

const client1 = new Client('username1', 'password1', 'localhost');
const client2 = new Client('username2', 'password2', 'localhost');

您的价格映射（从int到Client）将如下所示：

const price = {
    1: client1,
    2: client2
};

现在，您可以将其序列化为JSON：

const json = JSON.stringify(price);

或者从JSON解析出来：

const price = JSON.parse(json);

但是，如果您真的想使用Map，这里有一个教程供您参考。

class Client {
    constructor(username, password, host) {
        this.username = username;
        this.password = password;
        this.host = host;
    }
}

const client1 = new Client('username1', 'password1', 'localhost');
const client2 = new Client('username2', 'password2', 'localhost');

const price = {
    1: client1,
    2: client2
};

const json = JSON.stringify(price);

const price = JSON.parse(json);