Skip to content

HTML dependency for a downstream package's own JS/CSS bundle

Source: R/page.R
page_react_dep.Rd

Convenience mirroring Python's page_react_dep(). It is versioned by the JS file's mtime, so the /lib/{name}-{version}/ URL changes on every rebuild and the browser re-fetches. That is what you want while developing and the wrong thing for a published package — an mtime is whatever the install happened to write, so it is neither stable across machines nor meaningful to a reader. There is no version argument on purpose: a package shipping a fixed version should build its own htmltools::htmlDependency (the same advice as for a classic, non-module bundle), which is five lines and leaves nothing about the dependency implicit.

Usage

page_react_dep(
  src_dir,
  js_file = "ui.js",
  css_file = "ui.css",
  name = basename(src_dir)
)

Arguments

src_dir

Directory containing the JS/CSS. Required; Python infers this from the calling module's __file__ when omitted, which R has no equivalent of.

js_file

JS filename within src_dir. Defaults to "ui.js", matching Python; attached only if the file exists.

css_file

CSS filename within src_dir. Defaults to "ui.css", matching Python; attached only if the file exists. NULL to skip.

name

Dependency name; defaults to basename(src_dir).

Value

An htmltools::htmlDependency.

Details

The script tag is emitted as type="module". A classic <script defer> tag throws on the bundle's first import. type="module" is implicitly deferred, so no defer attribute is needed. If your bundle is a classic (non-module) script, build an htmltools::htmlDependency directly instead of using this helper.

Both the script and the stylesheet are attached only when the file exists inside src_dir, so a bundle that ships no CSS — or that has not been built yet — does not emit a tag pointing at a 404. Pass css_file = NULL to never attach a stylesheet. A missing js_file warns, since it is the entry point and an empty dependency would otherwise fail silently.

A missing src_dir errors, where a missing js_file only warns. Shiny serves the directory's files, so a directory that does not exist can only produce 404s for every asset the page references — a bug every time, and one that is far cheaper to see at page-build time than in the browser's network tab. Matches Python's page_react_dep(), which raises NotADirectoryError.