pxt-calliope/docs/reference/js/libraries.md
2016-03-25 16:47:20 -07:00

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# Create and Use Libraries
Libraries are scripts with functions that you can use in other scripts. #docs #libraries #language #library
### @parent js/language
Libraries are scripts with functions that you can use in other scripts. For example, `game` is a library of game-related functions that you can use in your scripts.
Benefits of using libraries:
* **reuse code** between scripts
* **collaborate** with other people on a project by combining scripts into a library
### Add a library
To add a library to a script:
1. Open a script in the [Touch Develop editor](/microbit/js/editor) and then click `script` (in the upper-right corner).
2. Click `+` **add new**.
3. Click `library`.
4. Choose the library you want to use or search for a library (such as `game`).
Once you've added a library to your script, you can use any of the library's non-private [functions](/microbit/js/function). Here's how:
* on the [Code Keyboard](/microbit/js/editor) click the button with the library's name (for example, `micro:bit` and `micro:bit game` are library buttons). The functions in the library have a button on the Code Keyboard.
### Create a library
Creating and publishing a script as a library is easy. Here's how:
1. Open a script in the [Touch Develop editor](/microbit/js/editor), and then click `script`.
2. Click the script name to open the script properties.
3. Mark the `this script is a library` check box.
4. Click `script`.
5. Click `publish`.
Once a script is marked as a _library_ and published, it's immediately available to other people.
### Visibility
The following library items are not accessible by other scripts:
* data (global variables)
* functions marked as `private`
If you want to access global library variables from other scripts, you need to create [functions](/microbit/js/function) that pass values in and out of the library script.
### Library and function documentation
Be sure to document the purpose of your functions and libraries. Add a [comment](/microbit/js/comment) at the beginning of a library to describe the purpose of the library.
Use [comments](/microbit/js/comment) at the beginning of your [functions](/microbit/js/function) to describe the function's purpose. Comment text shows in the help area of the Code Keyboard when you insert the function.
### See also
[functions](/microbit/js/function), [Touch Develop Documentation](/microbit/js/contents)