🧩 Custom Elements Runtime

Ultra-lightweight, type-safe runtime for fast, reactive, and maintainable web components.

Build modern web components with strict TypeScript, zero dependencies, and a functional API. Designed for performance, standards compliance, and developer productivity.

🚀 Getting Started

Install

npm install @jasonshimmy/custom-elements-runtime

Import and use in your project

import { component, html } from '@jasonshimmy/custom-elements-runtime';

component('my-counter', {
  state: { count: 0 },
  template: ({ count }) => html`
    <button data-on-click="increment">Count: ${count}</button>
  `({ count }),
  increment(event, state) { state.count++; }
});

TypeScript support

All types and interfaces are available for auto-completion and strict typing in code editors. No extra configuration is needed.

Advanced usage

See the API Reference for advanced configuration, SSR, plugin system, global store, event bus, and more.

✨ Features

Stateless & Stateful Components: Define components with or without state for maximum flexibility and performance.
Reactive State & Attribute Sync: Automatic re-renders and attribute reflection for primitive keys. Direct assignment triggers batched updates.
Functional Templates & Styling: Use functions, tagged helpers (html, compile), or async Promises. Supports static and dynamic styles.
Refs & Computed Properties: Direct DOM access via data-ref and derived state with computed.
Declarative Event & Input Binding: Use data-on-*, data-model, and data-bind for type-safe event and input sync, including deep and nested state.
Global Store & Event Bus: Built-in reactive store and event bus for cross-component state and communication.
SSR & Hydration: Universal rendering, opt-in hydration, and template matching. SSR excludes refs, event listeners, and lifecycle hooks.
Error Boundaries & Focus Preservation: Robust error handling and input focus retention during updates.
Plugin System: Extend runtime with hooks (onInit, onRender, onError) for global/component logic.
Router: Lightweight, functional router with SSR/static site support, <router-view>, route params, and programmatic navigation.
Performance & Modularity: Smart DOM batching, tree-shakable exports, strict TypeScript, and modular functional API.

Limitations & Edge Cases

Templates require a single root node. Fragments are supported, but strict reconciliation and keys are recommended for robust updates.
Only one event handler per event type per element; handlers must be defined on the config object.
Controlled input sync always prioritizes user typing over state updates.
SSR hydration is opt-in via data-hydrate; refs, event listeners, and lifecycle hooks are excluded during SSR.
User-generated content is escaped in templates using html and compile helpers.
Only documented features are supported; undocumented features may not work as expected.
Plugin system hooks must be pure and side-effect free for best results.
Router requires template matching for SSR hydration; navigation is programmatic and declarative.

� Use Cases

Micro-frontends: Lightweight, isolated components
Progressive Enhancement: Add reactivity to existing sites
Design Systems: Reusable component libraries
SSR Applications: Universal rendering with hydration
Performance-Critical Apps: When bundle size matters
Web Standards: Future-proof, standards-based development
Static Site Generation: Pre-render routes for instant loads and SEO
Plugin-driven Architectures: Extend runtime with custom hooks

🖥️ SSR Highlights

Universal Rendering & SEO: Fast, standards-compliant HTML/CSS for instant loads and search optimization.
Opt-in Hydration: Hydrate only needed regions for efficient interactivity; templates must match for seamless transitions.
Fragment & Keyed Templates: Robust reconciliation for fragments and keyed nodes.
Error Boundaries & Compliance: Graceful fallback UI; lifecycle hooks and refs excluded for predictable SSR.
SSR Router Support: Match routes server-side for static site generation and universal rendering.

🛡️ Production-Readiness

Strict TypeScript, modular structure
Early returns, guard clauses, custom error types
No external dependencies
Manual input validation and error handling
Deep sanitization of user-generated content
Regression-tested features and API

⚡ Performance Features

Smart DOM batching and minimal re-renders
Tree-shakable exports for optimal bundle size
Modular functional API for code splitting
Zero dependencies for maximum speed
SSR and static site generation for instant loads
Input focus and selection preservation
Efficient attribute-state sync and event handling

Batched Updates & Caching: State changes are batched (RAF); templates and computed properties are cached for speed.
Memory Management: Automatic cleanup prevents leaks.
Focus & DOM Efficiency: Input focus is preserved; only changed DOM nodes are updated for optimal UX.
Async & Selective Rendering: Promises supported in templates; hydrate only marked regions for efficient SSR.

📚 Documentation

Advanced Use Cases: Patterns for event bus, store, plugin system, async templates, error boundaries, SSR, VDOM.
API Reference: All runtime exports, configuration options, and advanced patterns.
Core Concepts: State, attribute sync, event binding, input binding, global store, event bus, lifecycle, error boundaries, SSR, plugin system.
Data Model vs Data Bind: Comparison, use cases, modifiers, deep binding, edge cases.
Examples: Concise, accurate code for all features and patterns.
Form Input Bindings: All supported input types, modifiers, deep binding, edge cases, VDOM patching.
Framework Comparison: Unique features, tradeoffs, strengths, and when to choose each approach.
Framework Integration: Using with React, Vue, Angular, Svelte, and Lit.
Routing: Lightweight, functional router with SSR/static site support.
SSR: SSR, hydration, limitations, API.

See the API Reference for detailed usage, configuration options, and advanced patterns. For advanced topics, see the linked docs above.

Local development

Clone this repository
Run the examples: npm run dev