js json 增加字段

let jsonObj = {
  "name": "John",
  "age": 30
};

// 增加一个新的字段 "city"
jsonObj.city = "New York";

console.log(jsonObj);
// 输出: { name: 'John', age: 30, city: 'New York' }

let jsonObj = {
  "name": "John",
  "age": 30
};

// 增加一个新的字段 "city"
jsonObj["city"] = "New York";

console.log(jsonObj);
// 输出: { name: 'John', age: 30, city: 'New York' }

let jsonObj = {
  "name": "John",
  "age": 30
};

let newField = "country";
let newValue = "USA";

jsonObj[newField] = newValue;

console.log(jsonObj);
// 输出: { name: 'John', age: 30, country: 'USA' }

let jsonString = '{"name": "John", "age": 30}';
let jsonObj = JSON.parse(jsonString);

jsonObj.city = "New York";

let updatedJsonString = JSON.stringify(jsonObj);
console.log(updatedJsonString);
// 输出: {"name":"John","age":30,"city":"New York"}

let jsonObj = {
  "name": "John",
  "age": 30
};

let updatedJsonObj = { ...jsonObj, city: "New York" };

console.log(updatedJsonObj);
// 输出: { name: 'John', age: 30, city: 'New York' }