Chalarangelo/30-seconds-of-code

---
title: Check if a JavaScript collection is empty
shortTitle: Value is empty
type: tip
language: javascript
tags: [type,array,object,string]
cover: mountain-lake
excerpt: Quickly determine if a collection of values is empty in JavaScript.
listed: true
dateModified: 2024-06-10
---

When we say a collection of values is _empty_, we mean that it has no elements with meaningful values. In JavaScript, we can consider an array, object, or string as empty if it has no elements, properties, or characters, respectively.

While arrays and strings share a `length` property, objects don't have a direct way to determine their size. In order to do so, we can use `Object.keys()` to get an **array of the object's keys** and then check its length. Luckily, `Object.keys()` also works on arrays and string, returning their **indices** as strings.

Given this information, we can use `Array.prototype.length` to check if the resulting **keys are empty**. If the value is `null` or `undefined`, we can consider it empty as well.

```js
const isEmpty = val =>
  val === null || val === undefined || !Object.keys(val).length;

isEmpty([]);              // true
isEmpty([1, 2]);          // false
isEmpty({});              // true
isEmpty({ a: 1, b: 2 });  // false
isEmpty('');              // true
isEmpty('text');          // false
isEmpty(null);            // true
isEmpty(undefined);       // true
```