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Hello Console

How to set up the basic development environment and run your first program

Install the CLI

xs-dev can be installed globally using the NodeJS package manager of your choice.

npm install -g xs-dev
pnpm install -g xs-dev
yarn global add xs-dev

Setup system tooling

As specified in the setup documentation, the Moddable SDK and associated tooling is installed using the following command:

xs-dev setup

This will determine the correct tooling to install based on your operating system.

Windows support is currently in beta

Once this process is done, you should see a success message:

Moddable SDK successfully set up! Start a new terminal session and run the "helloworld example": xs-dev run --example helloworld

or on Windows, you should see the following:

Moddable SDK successfully set up!
A shortcut to the Moddable Command Prompt has been created at \xs-dev\Moddable Command Prompt.lnk.
You should always use the Moddable Command Prompt when working with the Moddable SDK.
The Moddable Command Prompt will now open for you in a new Window. Please close this Command Prompt and use the Moddable Command Prompt instead.
As a next step, try running the "helloworld example" in the Moddable Command Prompt: xs-dev run --example helloworld'

Run the Hello World example

To start a new terminal session, you can either execute your shell of choice (bash/zsh/fish), create a new terminal window / tab, or start the Moddable Command Prompt on Windows. This will ensure the expected tooling is available in your session PATH.

You can run any Moddable example included in the SDK. The “Hello World” example provides the simplest program to get started and can be run in the simulator:

xs-dev run --example helloworld

This will start up the debugger and simulator:

Moddable simulator app and debugger app running on MacOS

This will keep running until interrupted using the Ctrl+C keys in the terminal session or both apps are quit.

Keep exploring!

Use the --list-examples flag with the run command to search the extensive list of available examples to run in the simulator: xs-dev run --list-examples

When you’re ready to move on, it’s time to create your first project and control some hardware.


When attempting to run the Hello World example, if you continually see the following error (even after starting a new terminal session):

Moddable tooling required. Run 'xs-dev setup --device <computer os here>' before trying again.

There may be an issue with the terminal shell or command prompt using the correct environment configuration for xs-dev.

On “Unix-like” environments (MacOS, Linux), the env command should contain a reference to the MODDABLE environment variable:

env | grep MODDABLE

The above command should return something like MODDABLE=/Users/<username>/.local/share/moddable to indicate where the Moddable SDK has been installed in the filesystem.

Running xs-dev doctor command will display relevant info about the development environment, which can be helpful for debugging and sharing in support issues:

xs-dev environment info:
CLI Version 0.19.3
OS Darwin
Arch arm64
NodeJS Version v16.14.0 (/path/to/node)
Python Version 3.10.9 (/path/to/python)
Moddable SDK Version 3.5.0 (/path/to/moddable)
Supported target devices mac
If this is related to an error when using the CLI, please create an issue at "" with the above info.