'Import' assets as an URL pointing to the asset.

Example

First, install Parcel and this plugin the usual way.

In worker.js:

postMessage("Hi!");
/* do stuff */

In main.js:

import workerURL from "worker.js.as-url";

const worker = new Worker(workerURL);
/* do stuff */

Then run Parcel with a single entry point of main.js.

worker.js will have its dependencies bundled in, Babel run on it, and all the other processing of JavaScript that you'd expect, but it'll wind up in a separate file.

You also need to have a dummy worker.js.as-url file or else Parcel gets annoyed, but it can be empty - it's totally ignored.

This also works for, e.g., setting window.location, or using the tabs.executeScript WebExtension API. In fact, you can import any type of file as an URL just by adding an extra as-url extension to the filename.

Why?

Parcel comes with autodetection for some specific constructs where JavaScript needs to reference something by URL, but it's not complete. If you're using a lesser-used API or you're doing something that presents difficulties for static analysis (e.g., to pick an example not at random, while creating a WebExtension), Parcel probably won't be able to work its magic.

With this plugin, I was able to go from having many entry points that were redundant and brittle (no static assurance I wouldn't be changing a filename in one place but not another) to declaratively specifying these types of dependencies on URLs and, in the end, coming down to just one entry point with everything else discoverable from there.

See Parcel issues #661 and #2306 for some more context.

Really, this plugin is a hack - but it's a hack with quite some wheels on it. Perhaps in the future it won't be needed as Parcel's rough edges get progressively sanded down, but it does the job today.

A note on Parcel

Parcel's pretty great. That this plugin is possible (and easy! Go look at the code and how little of it there is) says to me that its internal design is fundamentally Right, and it's operating with the correct abstractions for a bundler.

License

This package is licensed under the Apache License, version 2.0.