Custom Elements
📅
What are Custom Elements?
Custom Elements is a browser API that enables you to define custom HTML tags with unique behavior. It's the foundation of Web Components.
What You'll Learn
✅ Basic Components — creating simple elements
✅ Lifecycle Management — from creation to disposal
✅ Attributes & Properties — reactivity and validation
✅ Advanced Techniques — inheritance and mixins
Live Example
<!-- Custom tag -->
<user-profile name="Anna"></user-profile>
<script>
class UserProfile extends HTMLElement {
connectedCallback() {
this.innerHTML = `<div>Hello, ${this.getAttribute('name')}!</div>`;
}
}
customElements.define('user-profile', UserProfile);
</script>
Why It Matters
- 🚀 Native browser support (no polyfills needed)
- 🔧 Works with React, Vue, and other frameworks
- 📦 Reusable across projects
SEO Best Practices
- Use semantic tag names (e.g.,
app-navigationnotmy-cool-element) - Include ARIA attributes for accessibility
- Avoid visual terms in naming (
red-button→primary-button)