Vite-plugin-cem NPM

vite-plugin-cem

npm GitHub

Build automaticaly the manifest of your custom-elements. This plugin use the @custom-elements-manifest/analyzer to build the manifest. Here is what the plugin does depending on the environnement.

Development: Serve the manifest and rebuild it on the fly.
Production: Build the final manifest.

See the custom-elements-manifest repository to get more information about the manifest.

Install

Run one of the following command to install the plugin.

$ npm i vite-plugin-cem --save-dev

Usage

Add VitePluginCustomElementsManifest plugin to vite.config.js and configure it :

import { defineConfig } from 'vite'
import VitePluginCustomElementsManifest from 'vite-plugin-cem';

export default defineConfig({
  plugins: [
    VitePluginCustomElementsManifest({
      files: ['./src/title-element.ts']
    })
  ]
})

Using the api-viewer-element in your html :

<body>
  <api-viewer src="/custom-elements.json" selected="title-element"></api-viewer>

  <script type="module" src="/src/main.ts"></script>
</body>

Plugins

This plugin support custom-elements-manifest/analyzer plugins. You can get more information about these plugins here. This is an example how to use plugins.

First install the plugin :

$ npm install --save-dev cem-plugin-jsdoc-example

And register it using the plugins field :

import { defineConfig } from 'vite'
import VitePluginCustomElementsManifest from 'vite-plugin-cem';
import { jsdocExamplePlugin } from 'cem-plugin-jsdoc-example';

export default defineConfig({
  plugins: [
    VitePluginCustomElementsManifest({
      files: ['./src/title-element.ts'],
      lit: true,
      plugins: [
        jsdocExamplePlugin(),
      ]
    })
  ]
})

Yes, it's pluginsception !

Config File

Similar to the @custom-elements-manifest/analyzer, you can utilize a configuration file. By default, it will attempt to load the custom-elements-manifest.config.mjs file located at the root of your project.

// It will attempt to load the `custom-elements-manifest.config.mjs` file by default
export default defineConfig({
  plugins: [
    VitePluginCustomElementsManifest()
  ]
})

You also have the option to specify a custom configuration file using the config option.

// Here, it will attempt to load the `cem.config.mjs` file
export default defineConfig({
  plugins: [
    VitePluginCustomElementsManifest({
      config: 'cem.config.mjs'
    })
  ]
})

Virtual import

You can employ virtual import to seamlessly utilize the manifest built into your code. To achieve this, simply include the following line:

import manifest from 'virtual:vite-plugin-cem/custom-elements-manifest';

Storybook Integration

For direct integration of your custom element with Storybook, utilize the following virtual import:

// .storybook/preview.ts
import { setCustomElementsManifest } from '@storybook/web-components'
import manifest from 'virtual:vite-plugin-cem/custom-elements-manifest';

setCustomElementsManifest(manifest)

Storybook with cem-plugin-better-lit-types

If you're leveraging the cem-plugin-better-lit-types plugin, enhance your Storybook integration with the following code:

// .storybook/preview.ts
import { createArgsExtractor, createLitRenderer } from 'cem-plugin-better-lit-types/storybook'
import manifest from 'virtual:vite-plugin-cem/custom-elements-manifest';

export const parameters = {
  docs: {
    extractArgTypes: createArgsExtractor(manifest),
  }
}

export const render = createLitRenderer({
  wrapSlots: true,
  joinArrays: true,
})

Options

This is all current options of the plugin :

export interface VitePluginCustomElementsManifestOptions extends CreateManifestOptions {
  /**
   * Define where will be serve the manifest.
   * This option only work in development mode.
   * @default '/custom-elements.json'
   */
  endpoint?: string,
  /**
   * Define where will be build the final manifest.
   * This option only work in production mode.
   * @default 'custom-elements.json'
   */
  output?: string,
  /**
   * Add the custom-elements-manifest field to the package.json.
   * @default false
   */
  packageJson?: boolean,
  /**
   * Register files which will be used to build the manifest.
   * You can use pattern to find files.
   * @default [] 
   */
  files?: string[],
  /**
   * Defines the name of your config file *(optional)*
   * @default 'custom-elements-manifest.config.mjs'
   */
  config?: string,
}

interface CreateManifestOptions {
  /**
   * Use the lit plugin to parse files
   */
  lit?: boolean,
  /**
   * Use the fast plugin to parse files
   */
  fast?: boolean,
  /**
   * Use the stencil plugin to parse files
   */
  stencil?: boolean,
  /**
   * Use the catalyst plugin to parse files
   */
  catalyst?: boolean,
  /**
   * Run the builder in dev mode.
   * @default false
   */
  dev?: boolean,
  /**
   * Use ``custom-elements-manifest/analyzer`` plugins.
   * Get more information about these plugins here:
   * 
   * https://custom-elements-manifest.open-wc.org/analyzer/plugins/intro/
   */
  plugins?: Plugin[], 
  /**
   * Custom override for source file creation in module generation.
   * For more details on this feature, refer to:
   *
   * https://custom-elements-manifest.open-wc.org/analyzer/plugins/authoring/#overriding-sourcefile-creation
   *
   * @param {Object} options - The options object.
   * @param {Typescript} options.ts - The TypeScript instance.
   * @param {string[]} options.globs - An array of glob patterns.
   * @returns {SourceFile[]} An array of SourceFile.
   */
  overrideModuleCreation?: ({ ts, globs }: { ts: Typescript, globs: string[] }) => SourceFile[];
}