Anisubhra Sarkar (Ani)

Posted on Aug 24

What Are Web Components? A Complete Guide to Their Usage and Benefits

#webdev #webcomponents #frontend #shadowdom

Modern web development has evolved rapidly in the past decade. With the rise of complex applications, developers often face challenges in building reusable, maintainable, and encapsulated UI elements. This is where Web Components come in — a set of web platform features that allow developers to create reusable custom elements with their own functionality and styling, independent of the rest of the codebase.

What Are Web Components?

Web Components are a collection of web standards that enable the creation of custom, reusable, and encapsulated HTML elements. Unlike traditional components tied to frameworks like React, Angular, or Vue, Web Components are native browser features, meaning they work without additional libraries.

They are built on four main specifications:

Custom Elements
Define your own HTML elements with custom behavior.
Example: <user-card></user-card> could represent a reusable profile card.
Shadow DOM
Provides encapsulation for component structure and styles.
Ensures that CSS and JavaScript inside the component don’t leak into the global scope.
HTML Templates
Use the <template> tag to define reusable chunks of HTML that aren’t rendered until needed.
Helps in keeping markup clean and efficient.
ES Modules
Allow components to be organized, imported, and reused across different projects.
Encourages modular development.

Example: A Simple Web Component

Here’s a basic <user-card> component that displays a user’s name and email:

<user-card></user-card>

<script>
  class UserCard extends HTMLElement {
    constructor() {
      super();

      // Attach Shadow DOM
      const shadow = this.attachShadow({ mode: 'open' });

      // Template for the card
      shadow.innerHTML = `
        <style>
          .card {
            padding: 1rem;
            border: 1px solid #ccc;
            border-radius: 8px;
            font-family: sans-serif;
            max-width: 200px;
          }
          .name {
            font-weight: bold;
            margin-bottom: 0.5rem;
          }
        </style>
        <div class="card">
          <div class="name">John Doe</div>
          <div class="email">johndoe@example.com</div>
        </div>
      `;
    }
  }

  // Register the custom element
  customElements.define('user-card', UserCard);
</script>

Now you can use <user-card></user-card> just like a regular HTML tag, and it will render the card with its own encapsulated styles.

Why Are Web Components Used?

1. Reusability

Build once, reuse everywhere — across multiple projects, frameworks, or plain HTML pages.

2. Encapsulation

Shadow DOM keeps styles and scripts scoped, preventing conflicts in large apps.

3. Framework Agnostic

Works natively with any framework or none at all.

4. Performance

Native browser support means minimal runtime overhead.

5. Design Systems

Perfect for building shared UI libraries used by multiple teams.

Libraries to Easily Build Web Components

While Web Components can be written in plain JavaScript, several libraries simplify the process by reducing boilerplate and providing extra features:

Lit → A lightweight library from Google that makes it simple to create Web Components with reactive properties and minimal syntax.
Stencil → Developed by the Ionic team, it generates standards-compliant Web Components and comes with features like JSX, TypeScript support, and lazy loading.
Hybrids → A declarative approach to building Web Components, using plain objects instead of classes.
FAST → A Microsoft project offering performant Web Components and utilities to build design systems.
SkateJS → A library that simplifies defining Web Components using functional patterns.

These libraries help developers avoid boilerplate, improve productivity, and provide patterns that make Web Components easier to adopt in real-world applications.

When Should You Use Web Components?

Cross-framework projects: If your app needs to work with React, Angular, Vue, or vanilla JS at the same time.
Design systems / UI libraries: When building a reusable, framework-agnostic component library.
Micro frontends: If different parts of your app are built with different technologies.
Standardized widgets: Embedding widgets (like charts, maps, or chatbots) into various applications.

Pros and Cons of Web Components

✅ Pros

Native browser support (no extra libraries needed).
Reusable and portable across projects and frameworks.
Encapsulation with Shadow DOM prevents CSS/JS conflicts.
Great for micro frontends and design systems.
Future-proof: Based on official web standards.

❌ Cons

Boilerplate can be verbose compared to frameworks like React.
Limited state management features (you often need extra libraries).
Not as developer-friendly for large apps (compared to React/Angular).
Browser support is good but older browsers may require polyfills.
Learning curve if you’re used to framework abstractions.

Final Thoughts

Web Components are not meant to replace frameworks like React or Angular but to complement them. They provide a native, standardized way of building reusable UI elements that integrate across different stacks.

If you’re building design systems, reusable widgets, or micro frontends, Web Components are an excellent choice. And with libraries like Lit, Stencil, or FAST, you can get the benefits of Web Components without the heavy boilerplate.

For large-scale apps with complex state management, you’ll likely still want to combine them with frameworks — but knowing Web Components gives you more flexibility and future-proofing in your frontend toolkit.

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