62 lines
3.1 KiB
Markdown
62 lines
3.1 KiB
Markdown
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---
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title: Prevent Object Mutation
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---
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 Remember to use <a>**`Read-Search-Ask`**</a> if you get stuck. Try to pair program  and write your own code 
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### Problem Explanation:
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We need to prevent `MATH_CONSTANTS` value from changing.
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##  Hint: 1
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* Use Object.freeze(obj) to prevent object from being changed.
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> _try to solve the problem now_
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## Spoiler Alert!
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**Solution ahead!**
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##  Basic Code Solution:
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```javascript
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function freezeObj() {
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"use strict";
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const MATH_CONSTANTS = {
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PI: 3.14
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};
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Object.freeze(MATH_CONSTANTS);
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try {
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MATH_CONSTANTS.PI = 99;
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} catch( ex ) {
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console.log(ex);
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}
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return MATH_CONSTANTS.PI;
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}
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const PI = freezeObj();
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```
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 <a href='https://codepen.io/dylantyates/pen/OwVxYB' target='_blank' rel='nofollow'>Run Code</a>
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# Code Explanation:
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By using Object.freeze() on `MATH_CONSTANTS` we can avoid manipulating it.
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#### Relevant Links
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* <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze' target='_blank' rel='nofollow'>Object.freeze()</a>
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##  NOTES FOR CONTRIBUTIONS:
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*  **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.
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* Add an explanation of your solution.
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* Categorize the solution in one of the following categories — **Basic**, **Intermediate** and **Advanced**. 
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* Please add your username only if you have added any **relevant main contents**. ( **_DO NOT_** _remove any existing usernames_)
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> See  <a href='http://forum.freecodecamp.com/t/algorithm-article-template/14272' target='_blank' rel='nofollow'>**`Wiki Challenge Solution Template`**</a> for reference.
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