Creating Web components using Svelte

Introduction

As a developer, one of the key principles is to strive for reusable code. Web components offer an elegant way to achieve this and can be used across web pages and web apps. This can improve development efficiency, as it reduces the amount of code that needs to be written and maintained. Additionally, it makes it easier to update and test code, as the custom elements can be isolated from the rest of the application.

What are web components?

Web components are a set of technologies that allow developers to create custom, reusable elements for use in web pages and web apps. These elements, called custom elements, are defined using JavaScript and can be used just like standard HTML elements, such as a <div> or a <button>.

Web components consist of four main technologies:

• Custom Elements: Allows you to define your own HTML tags.
• Shadow DOM: Enables encapsulation of the elements' styles and markup, so they don't interfere with the rest of the page.
• HTML Templates: Allows you to declare fragments of HTML that can be cloned and added to the DOM.
• ES Modules: JavaScript modules that allow you to organize your code and reuse it across different parts of your application.

In short, web components allow you to create custom, reusable HTML elements that can be used across your web pages and web apps. It's a way to build a more modular and maintainable web development. You basically bundle all your components' logic inside JavaScript, import your code into your HTML file and bam! You can use your shiny new component 😊

An example of using a web component:

<script src="<<path-to-component-file>>" type="module"></script>
<web-component customprop1="value1" customprop2="value3" />

Declaring a web component in Svelte

The team behind Svelte has made it simple to convert a standard component into a web component. You only need to add: <svelte:options tag="<<web-component-name>>" /> at the top of the component you want to make reusable.

Minimal example of a web component built using Svelte:

<svelte:options tag="web-component" />

<script>
  export let customprop1 = null
  export let customprop2 = null
</script>

<div>
  <h1>Hi from web component</h1>
</div>

After defining the component, you include it in your main JavaScript/TypeScript file, usually called main.js/main.ts. For production, it's recommended to bundle your code and make it available through a Content Delivery Network (CDN) before using it in your application.

Configuring vite.config.js

import { defineConfig } from 'vite'
import { svelte } from '@sveltejs/vite-plugin-svelte'
import sveltePreprocess from 'svelte-preprocess'

export default defineConfig({
  plugins: [
    svelte({
      preprocess: sveltePreprocess({}),
      exclude: /\.component\.svelte$/,
      emitCss: false,
    }),
    svelte({
      preprocess: sveltePreprocess(),
      include: /\.component\.svelte$/,
      compilerOptions: {
        customElement: true,
      },
      emitCss: false,
    }),
  ],
  build: {
    sourcemap: true,
    target: 'modules',
    lib: {
      entry: 'src/main.js',
      name: '<<name>>',
      fileName: 'components',
    },
  },
})

The code above takes all files with the naming pattern of *.component.svelte and packages them into a single components.js file, which can then be uploaded to a file storage service such as S3. Once imported into your project, you are able to use the component without restriction.

Conclusion

In conclusion, creating web components using Svelte is a powerful and efficient way for developers to create reusable code for web pages and web apps. Svelte's simplicity in converting standard components into web components, combined with the technologies of custom elements, shadow DOM, HTML templates, and ES modules, make it easy for developers to create custom HTML elements that can be used across their projects with ease. By bundling and uploading the web components to a CDN, developers can make them easily accessible for use in any application. Implementing web components using Svelte can not only improve development efficiency, reduce the amount of code that needs to be written and maintained, but also make updates and testing easier. Overall, Svelte provides a great solution for creating modular and maintainable web components. Happy coding!