js怎么声明json对象

let jsonObject = {
  "key1": "value1",
  "key2": "value2",
  "key3": {
    "subKey1": "subValue1",
    "subKey2": "subValue2"
  },
  "key4": [1, 2, 3, 4, 5]
};

let obj = {
  name: "John",
  age: 30,
  city: "New York"
};

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

let jsonStr = '{"name":"John","age":30,"city":"New York"}';

let obj = JSON.parse(jsonStr);
console.log(obj.name); // 输出：John