> For the complete documentation index, see [llms.txt](https://docs.thunkable.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.thunkable.com/~/changes/wHhkjLVeheBnfbpghRnw/functions.md).

# Functions

## Function Overview

A function is a block of code that performs a specific task. If you use the same set of code multiple times in your project, you can work more efficiently by using blocks. Clear function names also make your code more readable.

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2FFzTq7nyIeEX2rYVeaGne%2FnofunctionsH.png?alt=media\&token=a98e0408-3a56-4d58-a685-25c82616cd8c)

## Video Tutorial

You can view a video tutorial on using functions here:

{% embed url="<https://www.youtube.com/watch?v=3jS3F3IRQB0>" %}

## Create a function

You can use the following block to create a function and give it a name:

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2Fue6wlCzxR130XW67jZI5%2Fdosomething.png?alt=media\&token=b2e07513-eede-409d-94f7-2f021b71a806)

One example of a function is below. This function will create and shuffle a list of items.

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2FOegMdluGVpuS9DvmmsA2%2Fshuffle.png?alt=media\&token=5797c869-a0aa-4873-a08e-2146974ffb53)

After you have created your function, you can simply use it at any time using the function block you have named:

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2FFAWasGYf51v0KgB979Fo%2Fcallshuffle.png?alt=media\&token=d533c7ea-590a-4b3c-9023-b9a80471a623)

## Create a function with an output

You can also create a function that returns a specific output.

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LAn5scXl2uqUJUOqkJo%2F-MBmyLkaLb0XFn8rjwoA%2F-MBnDFgRiSp4Hg9osvFn%2Fdoandreturn.png?alt=media\&token=38280a10-4084-4f09-a6db-5d7bd3b958ea)

### Conditional Outputs

You can add multiple `return` blocks to your function. This allows you to return a different output based on some conditions.

For example, this function will take a rating out of 100, and return a description of the quality of the item being reviewed:

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LAn5scXl2uqUJUOqkJo%2F-MBmyLkaLb0XFn8rjwoA%2F-MBnEGfugDVrF6z8coeU%2Fqualfunc.png?alt=media\&token=482b86ca-78c9-4a64-b25e-c9c619e7d6f1)

The function will break when the `return` block is fired. For example, in the above example, if the quality rating is 100, the function will return **Perfect** and then stop. It will not run the other tests, and won't return **Excellent**. **Good**, **Fine**, etc.

## Inputs and Functions

You can click the gear icon to add inputs to your functions.&#x20;

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2F95kR5oVLLJXC8gUU3QpS%2Fdosomething2.png?alt=media\&token=66f51e29-343c-497c-9ee1-754553af879a)

You can then treat that input as a local variable in your function.

In this example, the function `change font size` takes a number as an input and sets the text on a Screen to this font size. The number can be fed in as the number selected on a [Slider](/~/changes/wHhkjLVeheBnfbpghRnw/slider.md), or the user can click a Reset [Button](/~/changes/wHhkjLVeheBnfbpghRnw/button.md) to set the font size back to 18.

![](https://1223006790-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LAn5scXl2uqUJUOqkJo-84897653%2Fuploads%2FqUvaCZe6FlwacjCc3rAb%2Fchange%20font%20size.png?alt=media\&token=eadf8115-7fa7-4840-ad1f-1de538fca1b9)