---
title: "What is the difference between null and undefined in JavaScript?"  
description: "What is the difference between null and undefined in JavaScript?"  
author: "Sandra Emily"  
published: 2024-06-18  
updated: 2024-06-18  
canonical: https://www.mindstick.com/forum/160756/what-is-the-difference-between-null-and-undefined-in-javascript  
category: "javascript"  
tags: ["web development", "javascript", "front-end development"]  
reading_time: 2 minutes  

---

# What is the difference between null and undefined in JavaScript?

**What is the [difference between null](https://www.mindstick.com/forum/157810/explain-the-difference-between-null-and-undefined-in-javascript) and undefined in [JavaScript](https://www.mindstick.com/articles/874/how-to-create-watermark-text-for-textbox-by-using-javascript)?**

## Replies

### Reply by Ravi Vishwakarma

In JavaScript, [null](https://www.mindstick.com/forum/33922/how-to-use-null-coalescing-operator-in-c-sharp) and undefined are both values that represent the absence of a value, but they have distinct meanings and uses. \
Here's a detailed comparison between the two:

| Feature | ‘undefined’ | ‘null’ |
| --- | --- | --- |
| Definitions | It is the default value of variables that have been declared but not initialized. | It is used explicitly to signify that a variable should have no value. |
| Type | It's type is ‘undefined’. `typeof undefined; // “undefined”` | It's type is ‘object’. `typeof null; // ‘object’` |
| Usage | Automatically assigned to variables that are declared but not initialized. ```javascript let a; console.log(a); // undefined function foo() {} console.log(foo()); // undefined let obj = {}; console.log(obj.prop); // undefined ``` | Explicitly assigned to variables to represent "no value".\ Commonly used to reset or clear variables. ```javascript let b = null; console.log(b); // null let obj = { prop: null }; console.log(obj.prop); // null ``` |
| Comparisons | `undefined` and `null` are not strictly equal because they are different types. ```javascript console.log(undefined === null); // false ``` | `undefined` and `null` are loosely equal because they both represent an absence of value. ```javascript console.log(undefined == null); // true ``` |
| Common Issues | Using `undefined` can sometimes be a result of not properly initializing a variable. | `null` is used intentionally and explicitly. |

## Note:

`undefined` generally indicates that a variable has been declared but not yet assigned a value, while `null` is an assignment value that can be used to represent no value intentionally.


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Original Source: https://www.mindstick.com/forum/160756/what-is-the-difference-between-null-and-undefined-in-javascript

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