Check if an Object is Empty in TypeScript

# Check if an Object is Empty in TypeScript

To check if an object is empty in TypeScript:

Use the Object.keys() method to get an array of the object's keys.
Access the length property on the array.
If the length property is equal to 0, the object is empty.

index.ts

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interface Person {
  name?: string;
  age?: number;
  country?: string;
}

const person: Person = {};

if (Object.keys(person).length === 0) {
  console.log('Object is empty'); // 👉️ this runs
} else {
  console.log('Object is NOT empty');
}

const isEmpty = Object.keys(person).length === 0;
console.log(isEmpty); // 👉️ true

check if object is empty in typescript

The code for this article is available on GitHub

We used the Object.keys() method to get an array of the object's keys.

index.ts

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// 👇️ ['name', 'age']
console.log(Object.keys({ name: 'Bobby Hadz', age: 30 }));

The Object.keys method returns an empty array if the object has no key-value pairs (if it's empty).

If accessing the length property on the array of keys returns anything other than 0, then the object is not empty.

# Creating a reusable function to check if an object is empty

You can create a reusable function if have to perform the check often.

index.ts

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interface Person {
  name?: string;
  age?: number;
  country?: string;
}

const person: Person = {};

function isEmpty(obj: Record<string, any>): boolean {
  return Object.keys(obj).length === 0;
}

// 👇️ true
console.log(isEmpty(person));

// 👇️ false
console.log(isEmpty({ name: 'bobby hadz' }));

create reusable function to check if object is empty

The code for this article is available on GitHub

The function takes an object and returns true if the object is empty and false otherwise.

# Dealing with an edge case

Some objects that are created using the constructor functions that would return a false positive if we only check for the length of the object's keys.

index.ts

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function isEmpty(obj: Record<string, any>): boolean {
  return Object.keys(obj).length === 0;
}

console.log(isEmpty(new String())); // 👉️ true
console.log(isEmpty(new Number())); // 👉️ true

dealing with an edge case

Chances are you don't use these constructor functions with the new keyword in your code and that isn't an issue you have to worry about.

However, you could handle the edge case by checking if the object's constructor is equal to Object.

index.ts

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function isEmpty(obj: Record<string, any>): boolean {
  return Object.keys(obj).length === 0 && obj.constructor === Object;
}

console.log(isEmpty({})); // 👉️ true
console.log(isEmpty({ name: 'bobby hadz' })); // 👉️ false
console.log(isEmpty(new String())); // 👉️ false

We used the logical AND (&&) operator, so the isEmpty function only returns true if both conditions are met.

Here's what calling Object.keys() on a non-empty object looks like.

index.ts

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const obj = {a: 1, b: 2};

console.log(Object.keys(obj)); // 👉️ ['a', 'b']

const isEmpty = Object.keys(obj).length === 0;
console.log(isEmpty); // 👉️ false

I've also written an article on how to check if a property exists in an object.

An alternative approach is to try to iterate over the properties of the object. If there is even a single iteration, then the object is not empty.

# Check if an Object is Empty using a `for...in` loop in TypeScript

This is a three-step process:

Use a for...in loop to iterate over the properties of the object.
If there is even a single iteration, the object isn't empty.
If there aren't any iterations, the object is empty.

index.ts

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interface Person {
  name?: string;
  age?: number;
  country?: string;
}

const person: Person = {};

function isEmpty(obj: Record<string, any>): boolean {
  for (const _key in obj) {
    return false;
  }
  return true;
}

console.log(isEmpty(person)); // 👉️ true

console.log(isEmpty({ name: 'James' })); // 👉️ false

check if object is empty using for in loop

The code for this article is available on GitHub

The isEmpty function takes an object and attempts to iterate over the properties of the passed-in object.

If there is even 1 iteration, we know that the object has at least 1 key-value pair and is not an empty object.

If there aren't any iterations, then the object is empty.

I'd stick to the Object.keys() approach because it is more direct and intuitive.

# Check if an Object is Empty using `lodash` in TypeScript

Alternatively, you can use the lodash.isEmpty() method.

Open your terminal in the root directory of your project and install lodash with the following 2 commands.

shell

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npm install lodash.isempty

npm install --save-dev @types/lodash.isempty

Now you can import and use the isEmpty() method from lodash.

index.ts

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import isEmpty from 'lodash.isempty';

console.log(isEmpty({})); // 👉️ true
console.log(isEmpty({ name: 'bobby hadz' })); // 👉️ false

check if object is empty using lodash

The code for this article is available on GitHub

The lodash.isempty method checks if the supplied value is an empty object, collection, Map or Set.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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Check if an Object is Empty in TypeScript