Chalarangelo/30-seconds-of-code

---
title: Check if a JavaScript object has a given value or key
shortTitle: Object has value or key
language: javascript
tags: [object]
cover: plant-corner
excerpt: When working with objects, you'll often need to check if a value or key exists, and these snippets will show you how to do just that.
listed: true
dateModified: 2024-02-10
---

When working with plain JavaScript objects, you'll often need to check if a value or key exists. While the JavaScript API for objects isn't as rich as that for arrays, it still provides a few methods that can help you with this task.

## Check if an object has a given value

In order to check if an object has a given value, you can use `Object.values()` to get all the values of the object. Then, use `Array.prototype.includes()` to check if the target value is included in the values array.


```js
const hasValue = (obj, value) => Object.values(obj).includes(value);

const obj = { a: 100, b: 200 };
hasValue(obj, 100); // true
hasValue(obj, 999); // false
```

## Check if an object has a given key

Checking if an object has a given key is equally as easy, using `Object.keys()` instead of `Object.values()`. Then, you can use `Array.prototype.includes()` to check if the target key is included in the keys array.

```js
const hasKey = (obj, key) => Object.keys(obj).includes(key);

const obj = { a: 100, b: 200 };
hasKey(obj, 'a'); // true
hasKey(obj, 'c'); // false
```

### Accounting for nested keys

Checking for **nested keys** is a bit more complex, but can be done with a little ingenuity.

Given an array of keys, you can use `Array.prototype.every()` to sequentially check the keys to the internal **depth of the object**. Using `Object.prototype.hasOwnProperty()`, you can then check if the object does not have the current key or is not an object, stop propagation and return `false`. Otherwise, assign the key's value to the object to use on the next iteration.

```js
const hasKeyDeep = (obj, keys) => {
  return (
    keys.length > 0 &&
    keys.every(key => {
      if (typeof obj !== 'object' || !obj.hasOwnProperty(key)) return false;
      obj = obj[key];
      return true;
    })
  );
};

let obj = {
  a: 1,
  b: { c: 4 },
  'b.d': 5
};
hasKeyDeep(obj, ['a']); // true
hasKeyDeep(obj, ['b']); // true
hasKeyDeep(obj, ['b', 'c']); // true
hasKeyDeep(obj, ['b.d']); // true
hasKeyDeep(obj, ['d']); // false
hasKeyDeep(obj, ['c']); // false
hasKeyDeep(obj, ['b', 'f']); // false
```