How to Check if a JSON Object is Empty or Not in JavaScript

To check if a JSON object is empty in JavaScript, use Object.keys():

let obj = {};
let isEmpty = Object.keys(obj).length === 0;
console.log(isEmpty); // true

In JavaScript, it’s often necessary to check whether a JSON object is empty. An empty object has no enumerable properties. This guide will cover various methods to determine if an object is empty, providing code examples and explanations for each approach.

Using Object.keys()

Object.keys() returns an array of a given object’s own enumerable property names. If the length of this array is 0, the object is empty.

Example 1: Checking an Empty Object

let obj = {};
let isEmpty = Object.keys(obj).length === 0;
console.log(isEmpty); // true

Explanation:

• Object.keys(obj): Retrieves an array of property names from the object obj.
• .length === 0: Checks if the array length is 0, indicating the object is empty.

Using Object.entries()

Object.entries() returns an array of a given object’s own enumerable string-keyed property [key, value] pairs. If the length of this array is 0, the object is empty.

Example 2: Checking an Empty Object

let obj = {};
let isEmpty = Object.entries(obj).length === 0;
console.log(isEmpty); // true

Explanation:

• Object.entries(obj): Retrieves an array of [key, value] pairs from the object obj.
• .length === 0: Checks if the array length is 0, indicating the object is empty.

Using JSON.stringify()

JSON.stringify() converts a JavaScript object to a JSON string. An empty object will be converted to "{}".

Example 3: Checking an Empty Object

let obj = {};
let isEmpty = JSON.stringify(obj) === '{}';
console.log(isEmpty); // true

Explanation:

• JSON.stringify(obj): Converts the object obj to a JSON string.
• === '{}': Checks if the JSON string is equal to "{}", indicating the object is empty.

Using for…in Loop

The for...in loop iterates over an object’s enumerable properties. If no iterations occur, the object is empty.

Example 4: Checking an Empty Object

let obj = {};
let isEmpty = true;

for (let key in obj) {
  if (obj.hasOwnProperty(key)) {
    isEmpty = false;
    break;
  }
}

console.log(isEmpty); // true

Explanation:

• for (let key in obj): Iterates over all enumerable properties of the object obj.
• if (obj.hasOwnProperty(key)): Checks if the property is a direct property of the object, not inherited.
• isEmpty = false: If the loop runs, the object is not empty, so isEmpty is set to false.

Conclusion

Checking if a JSON object is empty in JavaScript can be done using several methods, including Object.keys(), Object.entries(), JSON.stringify(), and a for...in loop. Each method is suitable for different scenarios, ensuring that you can accurately determine whether an object has properties or not. By understanding these techniques, you can write more robust and maintainable code.