How to Check the Type of JSON Object in JavaScript?

You can check the type of a JSON object in JavaScript using the typeof operator. However, typeof will always return "object" for a JSON object, regardless of its actual data type.

To determine the specific type of data within a JSON object, you can use the following methods:

1. Using typeof for Primitive Values

If you want to check the type of a primitive value within a JSON object, you can use the typeof operator directly on the value.

Example:

const jsonObject = {
  "name": "John Doe",
  "age": 30,
  "isStudent": false
};

console.log(typeof jsonObject.name); // Output: string
console.log(typeof jsonObject.age); // Output: number
console.log(typeof jsonObject.isStudent); // Output: boolean

2. Using Object.prototype.toString.call() for Complex Types

For more complex types like arrays or objects, you can use the Object.prototype.toString.call() method. This method returns a string representation of the object's type.

Example:

const jsonObject = {
  "name": "John Doe",
  "age": 30,
  "hobbies": ["reading", "coding", "traveling"]
};

console.log(Object.prototype.toString.call(jsonObject.hobbies)); // Output: [object Array]

3. Using Custom Functions

You can also create custom functions to check the type of a JSON object based on your specific requirements. For instance, you could check for the presence of certain properties or methods to identify the object's type.

Example:

function isArray(obj) {
  return Object.prototype.toString.call(obj) === '[object Array]';
}

const jsonObject = {
  "name": "John Doe",
  "age": 30,
  "hobbies": ["reading", "coding", "traveling"]
};

console.log(isArray(jsonObject.hobbies)); // Output: true

By using these techniques, you can effectively check the type of JSON objects in JavaScript.