js 获取json对象值

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

let name = jsonObject.name; // "John"
let age = jsonObject.age; // 30
let city = jsonObject.city; // "New York"

let propertyName = "name";
let name = jsonObject[propertyName]; // "John"

if (jsonObject.hasOwnProperty('nonExistentProperty')) {
  let value = jsonObject.nonExistentProperty;
} else {
  console.log('Property does not exist');
}

let value = jsonObject?.nonExistentProperty; // undefined，不会报错

let jsonObject = {
  "first-name": "John",
  "last name": "Doe"
};

let firstName = jsonObject['first-name']; // "John"
let lastName = jsonObject['last name']; // "Doe"

let propertyName = prompt("Enter a property name:");
let value = jsonObject[propertyName]; // 根据用户输入获取值