如何在 JavaScript 中处理嵌套 JSON 数据？

处理 JSON 数据时，经常会遇到嵌套结构，比如对象中包含对象、对象中包含数组，或者两者混合的复杂结构。在解析 API 响应或处理复杂数据集时，高效处理此类数据至关重要。本指南将探讨如何在 JavaScript 中访问和处理嵌套 JSON 数据。

完整代码示例

下方展示了如何通过一段完整代码处理嵌套 JSON 数据：

      // Sample nested JSON structure
const user = {
    "id": 123,
    "name": "Jane Doe",
    "address": {
        "city": "New York",
        "postalCode": "10001"
    },
    "emails": ["[email protected]", "[email protected]"]
};

// Accessing a nested object (city)
const city = user.address.city;
console.log(city); // Outputs: "New York"

// Looping through a nested array (emails)
user.emails.forEach((email) => {
    console.log(email);
});
// Outputs: "[email protected]", "[email protected]"

// Handling deeply nested data (postal code)
const postalCode = user.address.postalCode;
console.log(postalCode); // Outputs: "10001"

// Using optional chaining for safe access
const optionalPostalCode = user?.address?.postalCode;
console.log(optionalPostalCode); // Outputs: "10001"

// Accessing dynamic keys (address)
const key = "address";
const dynamicCity = user[key].city;
console.log(dynamicCity); // Outputs: "New York"