21 lines
398 B
Markdown
21 lines
398 B
Markdown
---
|
|
title: Value is undefined
|
|
tags: type
|
|
expertise: beginner
|
|
cover: blog_images/peaches.jpg
|
|
firstSeen: 2018-01-16T16:50:21+02:00
|
|
lastUpdated: 2020-10-20T23:02:01+03:00
|
|
---
|
|
|
|
Checks if the specified value is `undefined`.
|
|
|
|
- Use the strict equality operator to check if `val` is equal to `undefined`.
|
|
|
|
```js
|
|
const isUndefined = val => val === undefined;
|
|
```
|
|
|
|
```js
|
|
isUndefined(undefined); // true
|
|
```
|