---
title: Prevent Object Mutation
---
![:triangular_flag_on_post:](https://forum.freecodecamp.com/images/emoji/emoji_one/triangular_flag_on_post.png?v=3 ":triangular_flag_on_post:") Remember to use <a>**`Read-Search-Ask`**</a> if you get stuck. Try to pair program ![:busts_in_silhouette:](https://forum.freecodecamp.com/images/emoji/emoji_one/busts_in_silhouette.png?v=3 ":busts_in_silhouette:") and write your own code ![:pencil:](https://forum.freecodecamp.com/images/emoji/emoji_one/pencil.png?v=3 ":pencil:")

### Problem Explanation:

_You need to freeze the `MATH_CONSTANTS` object so that no one is able to alter the value of `PI`, add, or delete properties ._

## ![:speech_balloon:](https://forum.freecodecamp.com/images/emoji/emoji_one/speech_balloon.png?v=3 ":speech_balloon:") Hint: 1

*   _Use `Object.freeze()` to prevent mathematical constants from changing._

> _try to solve the problem now_

## Spoiler Alert!

![warning sign](//discourse-user-assets.s3.amazonaws.com/original/2X/2/2d6c412a50797771301e7ceabd554cef4edcd74d.gif)

**Solution Ahead!**

## ![:beginner:](https://forum.freecodecamp.com/images/emoji/emoji_one/beginner.png?v=3 ":beginner:") Basic code solution:
```javascript
    function freezeObj() {
      "use strict";
      const MATH_CONSTANTS = {
        PI: 3.14
      };

      Object.freeze(MATH_CONSTANTS);
      
      try {
        MATH_CONSTANTS.PI = 99;
      } catch(ex) {
        console.log(ex);
      }
      return MATH_CONSTANTS.PI;
    }
    
    const PI = freezeObj();
```
# Code Explanation:

By using Object.freeze() on `MATH_CONSTANTS` we can avoid manipulating it.

### Resources
- ["Object.freeze()" - *MDN Javascript reference*](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze)

## ![:clipboard:](https://forum.freecodecamp.com/images/emoji/emoji_one/clipboard.png?v=3 ":clipboard:") NOTES FOR CONTRIBUTIONS:

*   ![:warning:](https://forum.freecodecamp.com/images/emoji/emoji_one/warning.png?v=3 ":warning:") **DO NOT** add solutions that are similar to any existing solutions. If you think it is **_similar but better_**, then try to merge (or replace) the existing similar solution.
*   Add an explanation of your solution.
*   Categorize the solution in one of the following categories — **Basic**, **Intermediate** and **Advanced**. ![:traffic_light:](https://forum.freecodecamp.com/images/emoji/emoji_one/traffic_light.png?v=3 ":traffic_light:")