freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-algorithm-scripting/truncate-a-string/index.md

---
title: Truncate a String
---
![: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:

We need to reduce the length of the string or **truncate** it if it is longer than the given maximum length specified and add `...` to the end. If it is not that long then we keep it as is.

#### Relevant Links

*   <a href='https://github.com/FreeCodeCamp/FreeCodeCamp/wiki/JS-String-Prototype-Slice' target='_blank' rel='nofollow'>String.prototype.slice()</a>

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

Strings are immutable in JavaScript so we will need a new variable to store the truncated string.

> _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 need to use the slice() method and specify where to start and where to stop.

> _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:

    function truncateString(str, num) {
      // Clear out that junk in your trunk
      if(str.length > num) {
        return str.slice(0,num)+"...";
      } else {
        return str;
      }
    }

![:rocket:](https://forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=3 ":rocket:") <a href='https://repl.it/CLjU/55' target='_blank' rel='nofollow'>Run Code</a>

### Code Explanation:

*   We start off with a simple `if` statement to determine one of two outcomes...
*   If our string length is greater than the `num` we want to truncate it, we return a slice of our string starting at character 0, and ending at `num`. We then append our `'...'` to the end of the string.
*   However, if above situation is not true, it means our string length is less than our truncation `num`. Therefore, we can just return the string.

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

    function truncateString(str, num) {
      return (str.length > num)?(str.slice(0,num)+"..."):str;
    }

![:rocket:](https://forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=3 ":rocket:") <a href='https://repl.it/CLjU/54' target='_blank' rel='nofollow'>Run Code</a>

### Code Explanation:

*   This solution is very similar to basic solution. To determine the new string, we use a ternary operator. In our ternary operation, if `str.length` is larger than `num`, we return a new string which is slice of our string starting at character 0, and ending at `num` and the `'...'` is appended to the end of our new string. If `str.length` is less than or equal to `num`, we return the string without any truncation.

*   **NOTE** In order to understand the above code, you need to understand how a Ternary Operator works. The Ternary Operator is frequently used as a shortcut for the `if` statement and follows this format: `condition ? expr1 : expr2`. If the `condition` evaluates to true, the operator returns the value of `expr1`. Otherwise, it returns the value of `expr2`.

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator' target='_blank' rel='nofollow'>Conditional (ternary) Operator</a>
*   <a href='https://github.com/FreeCodeCamp/FreeCodeCamp/wiki/JS-String-Prototype-Slice' target='_blank' rel='nofollow'>String.prototype.slice()</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:")
*   Please add your username only if you have added any **relevant main contents**. (![:warning:](https://forum.freecodecamp.com/images/emoji/emoji_one/warning.png?v=3 ":warning:") **_DO NOT_** _remove any existing usernames_)

> See ![:point_right:](https://forum.freecodecamp.com/images/emoji/emoji_one/point_right.png?v=3 ":point_right:") <a href='http://forum.freecodecamp.com/t/algorithm-article-template/14272' target='_blank' rel='nofollow'>**`Wiki Challenge Solution Template`**</a> for reference.