# Build rclnodejs

### Get ready for ROS 2

1. Install ROS 2 from binary package.

   ROS 2 is a cross-platform system, which covers Linux, macOS and Windows, and the `rclnodejs` module is developed against the [`master`](https://github.com/ros2/ros2/blob/master/ros2.repos) branch of ROS 2. You can download the latest binary packages from the [ROS 2 nightly builds](https://github.com/ros2/ros2/releases/tag/release-rolling-nightlies) and follow the instructions of [Linux](https://docs.ros.org/en/lyrical/Installation/Ubuntu-Install-Debians.html)/[Windows](https://docs.ros.org/en/lyrical/Installation/Windows-Install-Binary.html) to setup the environment. Supported ROS 2 distributions: Rolling, Lyrical, Kilted, Jazzy, and Humble.

2. Build ROS 2 from scratch.

   Alternatively, you can build ROS 2 from scratch. Please select the platform you want to work on, then reference the instructions of [Linux](https://docs.ros.org/en/lyrical/Installation/Alternatives/Ubuntu-Development-Setup.html#)/[Windows](https://docs.ros.org/en/lyrical/Installation/Alternatives/Windows-Development-Setup.html) to build ROS 2 (please build with flag `--merge-install`).

### Install `Node.js`

**Notice:**
`rclnodejs` requires Node.js version >= 20.20.2.

I install Nodejs from either:

- Node.js official [website](https://nodejs.org/en/)
- Node Version Manager ([nvm](https://github.com/creationix/nvm))

### C++ Toolchain Requirements

The native addon follows the ROS 2 distro toolchain requirement:

- Humble, Jazzy, and Kilted build with C++17.
- Post-Kilted distros, including Lyrical and newer Rolling snapshots, build with C++20.

If no prebuilt binary is available for your target, make sure your local compiler matches the required C++ standard before running `npm install`.

### Get Code

Open a terminal, and input:

```bash
git clone https://github.com/RobotWebTools/rclnodejs.git
```

### Build Module

Before you build the module, you should make sure the ROS2 environments were loaded. You can check if the `AMENT_PREFIX_PATH` environment variable was set:

- For Windows: `echo %AMENT_PREFIX_PATH%` in the command prompt.

- For Linux and macOS: `echo $AMENT_PREFIX_PATH` in the terminal.

If the `AMENT_PREFIX_PATH` is unset, you should load the ROS2 environments:

- For Windows, open the command prompt and run

```bash
  call <path\to\ros2>\install\local_setup.bat
```

- For Linux and macOS, open the terminal and run:

```bash
  source <path/to/ros2>/install/local_setup.bash
```

This `Node.js` module is built by [node-gyp](https://www.npmjs.com/package/node-gyp), all you have to do is just to run the following command:

```javascript
npm install
```

**Windows-specific**: make sure a Python 3.x interpreter is available in your `PATH` before running the command, as required by [node-gyp](https://github.com/nodejs/node-gyp#on-windows).

## Run Unit Tests

The test suite is implemented using the [mocha](https://www.npmjs.com/package/mocha) JavaScript test framework for node.js. Run the unit tests:

```javascript
npm run test
```

**Windows-specific**: the tests requires in a `Microsoft Visual Studio Native Tools command prompt`, and also make sure Python 3.x interpreter is first searched in your `PATH` before running te test. You can change it temporarily by:

```bash
  set PATH=<path\to\python 3.x>;%PATH%
```