Add external library

If you add a new dependency in your plugin with yarn add and use it with import * from "anyhting" it will be bundled automatically in the resulting .js file.

Disadvantages

This can be a problem in matter of SEO and performance. The bundle size can be very big (KiB, MiB) and as we all know it affects the page loading. Also, WordPress is a "modular" and high-extensible CMS (is it a CMS?) - Plugins and Themes bundles a lot of external libraries, too. So, why loading the content of a library twice?

Solution

The boilerplate comes out-of-the-box with a mechanism to automatically serve library files correctly. Enqueue the library files using the predefined Assets class. Following we explain the usage by an example:

• 1. Add your dependency with yarn add, e. g. yarn add sortablejs

• 2. Navigate to node_modules/sortablejs

• 3. The most libraries provide a CommonJS or UMD module. So, get the pathes to that files (if possible, also search for development files - mostly they do not contain .min.js)

• 4. Open plugins/your-plugin/scripts/Gruntfile.ts and add sortablejs to clean:npmLibs

clean: {
    npmLibs: {
        // [...]
        src: [
            /* [...] */
            "sortablejs" // <---
        ];
    }
}

• 5. Add the found module files to copy:npmLibs

copy: {
    npmLibs: {
        // [...]
        src: [
            // [...]
            "sortablejs/*.js" // <---
        ];
    }
}

• 6. If the module files are minified and contain Sourcemap files .js.map, also add the module files to strip_code:sourcemaps:

strip_code: {
    sourcemaps: {
        // [...]
        src: [
            // [...]
            "sortablejs/Sortable.min.js" // <---
        ];
    }
}

• 7. Run yarn grunt libs:copy so all library files gets copied to plugins/your-plugin/src/public/lib``
• 8. Open your Assets#enqueue_scripts_and_styles class and enqueue the library scripts and styles:

// .js
$useNonMinifiedSources = $this->useNonMinifiedSources();
$this->enqueueLibraryScript("sortablejs", [
    [$useNonMinifiedSources, 'sortablejs/Sortable.js'],
    'sortablejs/Sortable.min.js'
]);

• 9. If you have a look at your browser network log you see that the plugin automatically appends the right module version to the resource URL due to the cachebuster mechanism

• 10. The library is now automatically copied, loaded and served on your WordPress site. The last thing is telling webpack not bundling that package into the compiled .js files - instead it should refer to window.Sortable. For this, open plugins/your-plugin/scripts/webpack.config.ts:

import { createDefaultSettings } from "../../../common/webpack.factory";

export default createDefaultSettings((settings) => {
    Object.assign(settings.externals, {
        sortablejs: "Sortable"
    });
});

You can use the library without limitations in your TypeScript files:

import Sortable from "sortablejs";

Where do I know window.Sortable? Well, it is the exported name of the library. Most libraries provide such a name but there are also exceptions - then you must skip the Gruntfile.js modification and directly bundle it to your compiled .js files.

This seems to be a lot of work, but if you have made this twice you feel like "Wow, it's very easy and it works pretty" - and you never need the introduction above again. The above example does not include a .css but it can also be copied like this and enqueued with enqueueLibraryStyle().

Extend Compose and Webpack