javascript object 转 json

During the development process, we often encounter the need to convert JavaScript objects into JSON data. JSON (JavaScript Object Notation) is a lightweight data exchange format based on the syntax and structure of JavaScript objects and is widely used for front-end and back-end data transmission and storage.

In JavaScript, an object is a complex data type that can contain multiple properties and methods. When converting objects to JSON data, you can use the JSON.stringify() method, which serializes JavaScript objects into JSON data in the form of strings. Let's look at some examples:

// 定义一个 JavaScript 对象
var person = {
  name: "张三",
  age: 18,
  gender: "男"
};

// 将 JavaScript 对象转换为 JSON 数据
var json = JSON.stringify(person);

// 输出 JSON 数据
console.log(json);
// 输出：{"name":"张三","age":18,"gender":"男"}

In the above example, we define a JavaScript object named person, which has three properties: name, age and gender. We then use the JSON.stringify() method to convert the object to JSON data and output the JSON data to the console.

In addition to simple objects, the JSON.stringify() method can also serialize other data types, including arrays, strings, values, etc. Here are some examples:

// 序列化字符串
var str = "Hello World!";
var json = JSON.stringify(str);
console.log(json); // 输出：""Hello World!""

// 序列化数组
var arr = [1, 2, 3];
var json = JSON.stringify(arr);
console.log(json); // 输出："[1,2,3]"

// 序列化数值
var num = 123;
var json = JSON.stringify(num);
console.log(json); // 输出："123"

Note that when performing JSON serialization, if the object contains illegal values ​​such as functions, Undefined, etc., they will be ignored. At the same time, JSON.stringify() can also accept a second parameter, which is used to specify the attribute collection or custom serialization function that needs to be serialized.

Here are some examples:

// 序列化指定属性
var person = {
  name: "张三",
  age: 18,
  gender: "男",
  email: "zhangsan@example.com"
};

var json = JSON.stringify(person, ["name", "age"]);
console.log(json); // 输出："{"name":"张三","age":18}"

// 自定义序列化函数
var person = {
  name: "张三",
  age: 18,
  gender: "男",
  toJSON: function() {
    return {
      name: this.name,
      gender: this.gender
    };
  }
};

var json = JSON.stringify(person);
console.log(json); // 输出："{"name":"张三","gender":"男"}"

In the above example, we use the second parameter to specify that only the name and age attributes are serialized, or use a custom toJSON() function to Specify the serialization logic for the object.

In summary, converting JavaScript objects to JSON data is a common operation and can be achieved using the JSON.stringify() method. In addition to the basic object, array, string, and numeric types, you can also use the second parameter or a custom toJSON() function to customize the serialization logic.

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