# JavaScript: Get the Length of an Object With Object.keys()

> Get the number of properties in a JavaScript object by converting it to an array with Object.keys(), Object.values(), or a for...in loop

**URL:** https://sentry.io/answers/how-to-get-the-length-of-a-javascript-object/

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## The Problem

You want to determine the length of a JavaScript object, which is the number of properties in an object. Properties are also referred to as keys. Regular JavaScript objects don't have a `length` property, which is a property of an array. How do you determine the length of an object?

## The Solution

Convert the object to an array so that you can use the array [`length`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/length) property to determine the number of properties in the object. The `Object.keys()` method is suitable for most use cases.

### Using the `Object.keys()` Method

The [`Object.keys()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys) method takes in an object as an argument and returns an array of the object's properties:

```javascript
const obj = { name: 'Ben', age: 30, job: 'doctor' };
const arrFromObj = Object.keys(obj);
console.log(arrFromObj.length); // 3
```

This method is relatively new: it was added to the ES6 JavaScript language update. The `Object.keys()` method does not necessarily return all of the properties in an object. It returns an object's own [enumerable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties) string-keyed property names.

You can also use the [`Object.values()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values) method to return an array of the object's values or the [`Object.entries()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries) method to return an array containing the object's key-value pairs. Each key-value pair is added to a nested array.

### Using the `Object.getOwnPropertyNames()` Method

If you need to count non-enumerable properties, you can use the [`Object.getOwnPropertyNames()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames) method. It's similar to the `Object.keys()` method in that it returns an array of the properties of an object. The difference is that it also returns non-enumerable properties, except for properties that use a [symbol](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol) type.

```javascript
const obj = { name: 'Ben', age: 30, job: 'doctor' };
const arrFromObj = Object.getOwnPropertyNames(obj);
console.log(arrFromObj.length); // 3
```

### Using a For In Loop

You can also use a `for...in` loop to iterate through an object's enumerable properties and then use a variable that increments on each loop to count the number of properties:

```javascript
const obj = { name: 'Ben', age: 30, job: 'doctor' };
let length = 0;

for (const key in obj) {
  length++;
}

console.log(length); // 3
```

### Using Other Methods

Various other methods can be used to count properties, enumerable or non-enumerable, of an object as can be seen in this table: [Transversing JavaScript properties](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties#traversing_object_properties).

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*Source: [sentry.io/answers/how-to-get-the-length-of-a-javascript-object/](https://sentry.io/answers/how-to-get-the-length-of-a-javascript-object/)*