freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/convert-html-entities/index.md

---
title: Convert HTML Entities
---

# Convert HTML Entities

![HTML entities &'<>"](//discourse-user-assets.s3.amazonaws.com/original/2X/f/fc44d1dfbd3910e574cdedb0f05162f65b4cb7c4.jpg)

![: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:")

### ![:checkered_flag:](https://forum.freecodecamp.com/images/emoji/emoji_one/checkered_flag.png?v=3 ":checkered_flag:") Problem Explanation:

*   You have to create a program that will convert HTML entities from string to their corresponding HTML entities. There are only a few so you can use different methods.

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

*   You can use regular Expressions however I didn't in this case.

> _try to solve the problem now_

## ![:speech_balloon:](https://forum.freecodecamp.com/images/emoji/emoji_one/speech_balloon.png?v=3 ":speech_balloon:") Hint: 2

*   You will benefit from a chart with all the html entities so you know which ones are the right ones to put.

> _try to solve the problem now_

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

*   You should separate the string and work with each character to convert the right ones and then join everything back up.

> _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 convertHTML(str) {
  // Split by character to avoid problems.

  var temp = str.split('');

  // Since we are only checking for a few HTML elements, use a switch

  for (var i = 0; i < temp.length; i++) {
    switch (temp[i]) {
      case '<':
        temp[i] = '&lt;';
        break;
      case '&':
        temp[i] = '&amp;';
        break;
      case '>':
        temp[i] = '&gt;';
        break;
      case '"':
        temp[i] = '&quot;';
        break;
      case "'":
        temp[i] = "&apos;";
        break;
    }
  }

  temp = temp.join('');
  return temp;
}

//test here
convertHTML("Dolce & Gabbana");
```
### Code Explanation:

*   Assign **temp** to `str.split('')`, which creates an array containing each individual character in the passed in string.
*   Pass each character in the newly created array into a `switch()` statement.
*   Replace the HTML entities with their corresponding HTML entity string (i.e. `'&'` becomes `'&amp;'` in line 51)
*   `temp.join('')` converts the array of characters into a string to be returned.

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split' target='_blank' rel='nofollow'>str.split()</a>
*   <a href='https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/join' target='_blank' rel='nofollow'>arr.join()</a>
*   <a href='https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/switch' target='_blank' rel='nofollow'>switch statement</a>

## ![:sunflower:](https://forum.freecodecamp.com/images/emoji/emoji_one/sunflower.png?v=3 ":sunflower:") Intermediate Code Solution:

```javascript
function convertHTML(str) {
  // Use Object Lookup to declare as many HTML entities as needed.
  const htmlEntities = {
    "&" : '&amp;',
    "<" : "&lt;",
    ">" : "&gt;",
    '"' : "&quot;",
    "'" :"&apos;"
  }
  // Using a regex, replace characters with it's corresponding html entity
  return str.replace(/([&<>\"'])/g, match => htmlEntities[match]);
}

// test here
convertHTML("Dolce & Gabbana");
```

### Code Explanation:
*   Create an object to use the Lookup functionality and easily find the characters.
*   Use `replace()` to replace characters with regex. 
*   The first argument for `replace()` is a regex that catches all the target characters and puts them into a capturing group.
*   The second arguments for `replace()` is a function with the matched character as a parameter. It returns the correspondant entity from `htmlEntities`.

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace' target='_blank' rel='nofollow'>str.replace()</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp' target='_blank' rel='nofollow'>Regular Expressions</a>

## ![:rotating_light:](https://forum.freecodecamp.com/images/emoji/emoji_one/rotating_light.png?v=3 ":rotating_light:") Advanced Code Solution:

```javascript
function convertHTML(str) {
  // Use Object Lookup to declare as many HTML entities as needed.
  const htmlEntities={
    '&':'&amp;',
    '<':'&lt;',
    '>':'&gt;',
    '"':'&quot;',
    '\'':"&apos;"
  };
  //Use map function to return a filtered str with all entities changed automatically.
  return str.split('').map(entity => htmlEntities[entity] || entity).join('');
}

// test here
convertHTML("Dolce & Gabbana");
```

### Code Explanation:

*   Create an object to use the Lookup functionality and easily find the characters.
*   Split the original string by characters and use map to check for the changed html entity or use the same one.
*   The a function is added which is what returns the converted entity or the original one if there is no conversion.
*   Lastly we join all the characters once again.

**Note** that if you went the regex route then you don't need to join anything, just make sure you return the whole operation or save it to a variable and then return it.

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split' target='_blank' rel='nofollow'>str.split()</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map' target='_blank' rel='nofollow'>arr.map()</a>
*   <a href='https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/join' target='_blank' rel='nofollow'>arr.join()</a>

## ![: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:")