Explanation: Node.js - JavaScript and Sass tools

Node.js is a runtime environment which can execute JavaScript code outside a web browser. It is used widely for web development. Its package manager, npm, makes it easy to install virtually any JavaScript library.

Rhino uses Node.js to provide state of the art tools for working with JavaScript and Sass. In the future it might also become an easy way to add any JS library to your Shiny app.

The following functions require Node.js to work:

1. build_js()
2. build_sass() (with sass: node configuration in rhino.yml)
3. lint_js()
4. lint_sass()
5. test_e2e()

You don’t need to worry about Node.js most of the time. You need to install it on your system along with yarn (an alternative package manager for Node.js). The rest will be handled automatically.

Under the hood Rhino will create a .rhino/node directory in your project to store the specific libraries needed by these tools. This directory is git-ignored by default and safe to remove.

The build_sass() function is worth an additional comment. Depending on the configuration in rhino.yml it can use either the sass Node.js package or the sass R package. We recommend the Node.js version, as it is the primary, actively developed implementation of Sass. In contrast, the R package uses the deprecated LibSass implementation.