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Paclets

Wolfram Packages (Paclets)​

Paclets are the canonical format for distributing libraries (packages) for Wolfram Language interpreters (Wolfram Engine, WolframScript, Mathematica).

A paclet can be a compressed or uncompressed bundle that contains one or more packages plus metadata and optional assets (documentation, front-end resources, data, web assets).

Extensions for Wolfram Paclets​

You can write a normal Wolfram package for both Mathematica and WLJS that can take advantage of WLJS’s extra features when needed.

❓ What you can do with this:

  • Ship JavaScript and CSS assets that are automatically integrated into the runtime once the package is loaded.
  • Write a single package for WLJS, Mathematica, and WolframScript.
  • Expose folders from your paclet to an HTTP server.

❓ Will it work for exported notebooks?

  • Yes. JavaScript bundles can be compressed and embedded into the notebook if you enable this in Settings.
  • You can safely publish your notebook.
  • Anyone who doesn’t have those package assets installed will still be able to read the notebook without issues.
  • Everything is cached and updated whenever changes are made to the paclet.

Example​

Here’s how this might look in your PacletInfo:

PacletObject[
  <|
    "Name" -> "CoffeeLiqueur/SplatMesh",
    "License" -> "MIT",
    "Extensions" -> {
      {
        "Javascript",
        "Root" -> {"Assets", "Spark", "kernel.js"}
      },
      {
        "Javascript Bundle", (* only for exporting to HTML *)
        "Root" -> {"Assets", "Bundle", "bundle.js"}
      }
      <...>

Your package structure might look like this:

PacletInfo.wl
Kernel/
  Kernel.wl
  ...
Assets/
  Spark/
    kernel.js
...

Front-end Extensions​

These are special fields in the PacletInfo.wl file that describe what is added to the front-end runtime (i.e., what becomes globally available).

Mathematica uses a somewhat similar mechanism for adding new styles or extending context menus/palettes.

"Javascript"​

⚠️ Requires the "Root" option.

Use this to include .js files in the runtime. They are loaded before the notebook view and are never unloaded.

Dynamic imports of other assets from the root folder are supported.

"Javascript Bundle"​

⚠️ Requires the "Root" option.

Use this to include .js bundles (no dynamic imports; all-in-one) for notebooks exported as Static HTML or MDX.

It is not loaded into the runtime under normal circumstances. However, if someone opens a notebook without the required package/paclet installed, the bundle will be temporarily loaded to avoid rendering issues.

"CSS"​

⚠️ Requires the "Root" option.

Use this to include .css files in the runtime. They are loaded before the notebook view and are never unloaded.

The same CSS file will be imported and embedded into all exported notebooks.

Notes on Saving/Exporting Notebooks​

The listed third-party assets are not stored within the notebook by default to avoid unwanted copies of random bundles in all notebooks.

From the Settings menu you can:

  • Remove all cached assets from the WLJS Notebook app.
  • Remove all cached assets from opened (visible) notebooks.
  • Embed all assets into opened notebooks.

The last option lets you embed assets not only in saved notebooks but also in notebooks exported to Static HTML and MDX.

Examples​

Some packages published for both WLJS and Mathematica:

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