Blaze-NG

Appearance

Example: Dynamic Components ​

A plugin system with lazy loading, runtime template registration, and dynamic composition.

Plugin Architecture ​

handlebars
<template name="pluginHost">
  <div class="plugin-host">
    <nav class="plugin-nav">
      <h2>Plugins</h2>
      {{#each plugin in plugins}}
        <button class="plugin-tab {{#if (eq plugin.id activePluginId)}}active{{/if}}"
                data-plugin-id="{{plugin.id}}">
          <span class="plugin-icon">{{plugin.icon}}</span>
          {{plugin.name}}
          {{#if plugin.badge}}
            <span class="badge">{{plugin.badge}}</span>
          {{/if}}
        </button>
      {{/each}}
    </nav>

    <main class="plugin-content">
      {{#if activePlugin}}
        {{#if isPluginLoading}}
          <div class="loading-state">
            <div class="spinner"></div>
            <p>Loading {{activePlugin.name}}...</p>
          </div>
        {{else}}
          {{> Template.dynamic template=activePlugin.template data=activePlugin.data}}
        {{/if}}
      {{else}}
        <div class="welcome-state">
          <h2>Welcome</h2>
          <p>Select a plugin from the sidebar to get started.</p>
        </div>
      {{/if}}
    </main>
  </div>
</template>

Plugin Host Logic ​

ts
import { Template } from '@blaze-ng/templating-runtime';
import { Blaze } from '@blaze-ng/core';
import { SimpleReactiveSystem } from '@blaze-ng/core/testing';

Blaze.setReactiveSystem(new SimpleReactiveSystem());

// ── Plugin Registry ─────────────────────────────────────

const pluginRegistry = new Map();

/**
 * Register a plugin with the system.
 * @param {object} config - Plugin configuration.
 * @param {string} config.id - Unique plugin identifier.
 * @param {string} config.name - Display name.
 * @param {string} config.icon - Emoji icon.
 * @param {string} config.template - Template name to render.
 * @param {Function} [config.loader] - Async loader for lazy plugins.
 */
function registerPlugin(config) {
  pluginRegistry.set(config.id, {
    ...config,
    loaded: !config.loader, // Eager plugins are already loaded
  });
}

// ── Plugin Host Template ────────────────────────────────

Template.pluginHost.onCreated(function () {
  this.activePluginId = new ReactiveVar(null);
  this.isPluginLoading = new ReactiveVar(false);
  this.pluginData = new ReactiveVar({});
});

Template.pluginHost.helpers({
  plugins() {
    return Array.from(pluginRegistry.values());
  },
  activePluginId() {
    return Template.instance().activePluginId.get();
  },
  activePlugin() {
    const id = Template.instance().activePluginId.get();
    if (!id) return null;
    const plugin = pluginRegistry.get(id);
    if (!plugin?.loaded) return null;
    return {
      ...plugin,
      data: Template.instance().pluginData.get()[id] || {},
    };
  },
  isPluginLoading() {
    return Template.instance().isPluginLoading.get();
  },
});

Template.pluginHost.events({
  async 'click .plugin-tab'(event, instance) {
    const pluginId = event.currentTarget.dataset.pluginId;
    instance.activePluginId.set(pluginId);

    const plugin = pluginRegistry.get(pluginId);
    if (plugin && !plugin.loaded && plugin.loader) {
      instance.isPluginLoading.set(true);

      // Load the plugin (registers its template)
      await plugin.loader();
      plugin.loaded = true;

      instance.isPluginLoading.set(false);
      // Force reactivity update
      instance.activePluginId.set(pluginId);
    }
  },
});

Eager Plugins ​

These plugins are registered and available immediately:

Notes Plugin ​

handlebars
<template name="notesPlugin">
  <div class="notes-plugin">
    <div class="notes-toolbar">
      <button class="btn-new-note">+ New Note</button>
    </div>
    <div class="notes-layout">
      <ul class="notes-list">
        {{#each note in notes}}
          <li class="note-item {{#if (eq note.id activeNoteId)}}active{{/if}}"
              data-note-id="{{note.id}}">
            <strong>{{note.title}}</strong>
            <small>{{formatDate note.updatedAt}}</small>
          </li>
        {{/each}}
      </ul>
      {{#if activeNote}}
        <div class="note-editor">
          <input class="note-title-input" value="{{activeNote.title}}"
                 placeholder="Note title">
          <textarea class="note-body-input"
                    placeholder="Write something...">{{activeNote.body}}</textarea>
        </div>
      {{else}}
        <div class="no-note-selected">Select or create a note</div>
      {{/if}}
    </div>
  </div>
</template>
ts
Template.notesPlugin.onCreated(function () {
  this.notes = new ReactiveVar([
    { id: '1', title: 'Getting Started', body: 'Welcome to Notes!', updatedAt: new Date() },
    {
      id: '2',
      title: 'Ideas',
      body: 'Some ideas for the project...',
      updatedAt: new Date(Date.now() - 86400000),
    },
  ]);
  this.activeNoteId = new ReactiveVar(null);
});

Template.notesPlugin.helpers({
  notes() {
    return Template.instance().notes.get();
  },
  activeNoteId() {
    return Template.instance().activeNoteId.get();
  },
  activeNote() {
    const id = Template.instance().activeNoteId.get();
    return Template.instance()
      .notes.get()
      .find((n) => n.id === id);
  },
});

Template.notesPlugin.events({
  'click .note-item'(event, instance) {
    instance.activeNoteId.set(event.currentTarget.dataset.noteId);
  },
  'click .btn-new-note'(event, instance) {
    const notes = instance.notes.get();
    const newNote = {
      id: String(Date.now()),
      title: 'Untitled',
      body: '',
      updatedAt: new Date(),
    };
    instance.notes.set([newNote, ...notes]);
    instance.activeNoteId.set(newNote.id);
  },
  'input .note-title-input'(event, instance) {
    updateNote(instance, 'title', event.target.value);
  },
  'input .note-body-input'(event, instance) {
    updateNote(instance, 'body', event.target.value);
  },
});

function updateNote(instance, field, value) {
  const id = instance.activeNoteId.get();
  const notes = instance.notes
    .get()
    .map((n) => (n.id === id ? { ...n, [field]: value, updatedAt: new Date() } : n));
  instance.notes.set(notes);
}

// Register as eager plugin
registerPlugin({
  id: 'notes',
  name: 'Notes',
  icon: '📝',
  template: 'notesPlugin',
});

Timer Plugin ​

handlebars
<template name="timerPlugin">
  <div class="timer-plugin">
    <div class="timer-display">
      {{formatTimer elapsed}}
    </div>
    <div class="timer-controls">
      {{#if isRunning}}
        <button class="btn-pause">⏸ Pause</button>
      {{else}}
        <button class="btn-start">▶ Start</button>
      {{/if}}
      <button class="btn-reset">↺ Reset</button>
      <button class="btn-lap" {{#unless isRunning}}disabled{{/unless}}>Lap</button>
    </div>
    {{#if laps.length}}
      <table class="lap-table">
        <thead><tr><th>#</th><th>Lap Time</th><th>Total</th></tr></thead>
        <tbody>
          {{#each lap in laps}}
            <tr>
              <td>{{math (subtract laps.length @index) "+" 0}}</td>
              <td>{{formatTimer lap.split}}</td>
              <td>{{formatTimer lap.total}}</td>
            </tr>
          {{/each}}
        </tbody>
      </table>
    {{/if}}
  </div>
</template>
ts
Template.timerPlugin.onCreated(function () {
  this.elapsed = new ReactiveVar(0);
  this.isRunning = new ReactiveVar(false);
  this.laps = new ReactiveVar([]);
  this.intervalId = null;
  this.lastLapTime = 0;
});

Template.timerPlugin.onDestroyed(function () {
  if (this.intervalId) clearInterval(this.intervalId);
});

Template.timerPlugin.helpers({
  elapsed() {
    return Template.instance().elapsed.get();
  },
  isRunning() {
    return Template.instance().isRunning.get();
  },
  laps() {
    return Template.instance().laps.get();
  },
});

Template.timerPlugin.events({
  'click .btn-start'(event, instance) {
    instance.isRunning.set(true);
    const startTime = Date.now() - instance.elapsed.get();
    instance.intervalId = setInterval(() => {
      instance.elapsed.set(Date.now() - startTime);
    }, 10);
  },
  'click .btn-pause'(event, instance) {
    instance.isRunning.set(false);
    clearInterval(instance.intervalId);
  },
  'click .btn-reset'(event, instance) {
    instance.isRunning.set(false);
    instance.elapsed.set(0);
    instance.laps.set([]);
    instance.lastLapTime = 0;
    clearInterval(instance.intervalId);
  },
  'click .btn-lap'(event, instance) {
    const total = instance.elapsed.get();
    const split = total - instance.lastLapTime;
    instance.lastLapTime = total;
    instance.laps.set([{ split, total }, ...instance.laps.get()]);
  },
});

registerPlugin({
  id: 'timer',
  name: 'Timer',
  icon: '⏱',
  template: 'timerPlugin',
});

Lazy-Loaded Plugin ​

This plugin is loaded on demand when first activated:

ts
// Register with a loader function — template isn't defined yet
registerPlugin({
  id: 'weather',
  name: 'Weather',
  icon: '🌤',
  template: 'weatherPlugin',
  loader: async () => {
    // Simulate network delay
    await new Promise((resolve) => setTimeout(resolve, 1500));

    // Define the template at runtime
    Template.__define__('weatherPlugin', () => {
      // Return the template's render function
      return Blaze._TemplateWith({ cities: () => Template.instance().cities.get() }, () =>
        Template.weatherPluginContent(),
      );
    });
  },
});
handlebars
<!-- This template is loaded lazily -->
<template name='weatherPluginContent'>
  <div class='weather-plugin'>
    <div class='weather-grid'>
      {{#each city in cities}}
        <div class='weather-card'>
          <h4>{{city.name}}</h4>
          <div class='weather-icon'>{{city.icon}}</div>
          <div class='temperature'>{{city.temp}}°</div>
          <div class='condition'>{{city.condition}}</div>
        </div>
      {{/each}}
    </div>
  </div>
</template>

Recursive Components ​

A file tree browser built with recursive template inclusion:

handlebars
<template name="fileTree">
  <div class="file-tree">
    <h3>Project Files</h3>
    {{> fileNode node=root depth=0}}
  </div>
</template>

<template name="fileNode">
  <div class="file-node" style="padding-left: {{indent depth}}px">
    {{#if node.children}}
      <div class="folder" data-path="{{node.path}}">
        <span class="toggle">{{#if (isExpanded node.path)}}▼{{else}}▶{{/if}}</span>
        <span class="icon">📁</span>
        <span class="name">{{node.name}}</span>
      </div>
      {{#if (isExpanded node.path)}}
        {{#each child in node.children}}
          {{> fileNode node=child depth=(math depth "+" 1)}}
        {{/each}}
      {{/if}}
    {{else}}
      <div class="file">
        <span class="icon">{{fileIcon node.name}}</span>
        <span class="name">{{node.name}}</span>
        <span class="size">{{formatSize node.size}}</span>
      </div>
    {{/if}}
  </div>
</template>
ts
Template.fileTree.onCreated(function () {
  this.expandedPaths = new ReactiveVar(new Set(['/', '/src']));
});

Template.fileTree.helpers({
  root() {
    return {
      name: 'project',
      path: '/',
      children: [
        {
          name: 'src',
          path: '/src',
          children: [
            { name: 'index.ts', path: '/src/index.ts', size: 2048 },
            { name: 'utils.ts', path: '/src/utils.ts', size: 1024 },
            {
              name: 'components',
              path: '/src/components',
              children: [
                { name: 'App.ts', path: '/src/components/App.ts', size: 3072 },
                { name: 'Header.ts', path: '/src/components/Header.ts', size: 1536 },
              ],
            },
          ],
        },
        { name: 'package.json', path: '/package.json', size: 512 },
        { name: 'tsconfig.json', path: '/tsconfig.json', size: 256 },
        { name: 'README.md', path: '/README.md', size: 4096 },
      ],
    };
  },
});

Template.registerHelper('isExpanded', (path) => {
  const instance = Blaze.getView().templateInstance();
  // Walk up to find the fileTree instance
  let view = instance.view;
  while (view && !view.template?.viewName?.includes('fileTree')) {
    view = view.parentView;
  }
  const fileTree = view?.templateInstance();
  return fileTree?.expandedPaths.get().has(path);
});

Template.registerHelper('indent', (depth) => depth * 20);

Template.registerHelper('fileIcon', (name) => {
  if (name.endsWith('.ts')) return '🟦';
  if (name.endsWith('.json')) return '📋';
  if (name.endsWith('.md')) return '📄';
  return '📄';
});

Template.registerHelper('formatSize', (bytes) => {
  if (bytes < 1024) return `${bytes} B`;
  return `${(bytes / 1024).toFixed(1)} KB`;
});

Template.registerHelper('subtract', (a, b) => a - b);

Template.fileNode.events({
  'click .folder'(event, instance) {
    event.stopPropagation();
    const path = event.currentTarget.dataset.path;

    // Find the root fileTree instance
    let view = instance.view;
    while (view && !view.template?.viewName?.includes('fileTree')) {
      view = view.parentView;
    }
    const fileTree = view?.templateInstance();
    if (!fileTree) return;

    const expanded = new Set(fileTree.expandedPaths.get());
    if (expanded.has(path)) {
      expanded.delete(path);
    } else {
      expanded.add(path);
    }
    fileTree.expandedPaths.set(expanded);
  },
});

Styles ​

css
/* Plugin Host */
.plugin-host {
  display: grid;
  grid-template-columns: 220px 1fr;
  height: 100vh;
  font-family: system-ui, sans-serif;
}

.plugin-nav {
  background: #1e1e2e;
  color: white;
  padding: 1rem;
}

.plugin-tab {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  width: 100%;
  padding: 0.75rem;
  border: none;
  border-radius: 8px;
  background: transparent;
  color: #a1a1b5;
  cursor: pointer;
  font-size: 0.875rem;
  text-align: left;
}

.plugin-tab:hover {
  background: #313244;
  color: white;
}
.plugin-tab.active {
  background: #4f46e5;
  color: white;
}

.badge {
  margin-left: auto;
  background: #ef4444;
  color: white;
  padding: 0.125rem 0.375rem;
  border-radius: 999px;
  font-size: 0.6875rem;
}

.plugin-content {
  padding: 2rem;
}

/* Loading & welcome */
.loading-state,
.welcome-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 50vh;
  color: #64748b;
}

.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid #e2e8f0;
  border-top-color: #4f46e5;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Notes */
.notes-layout {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 1rem;
  margin-top: 1rem;
}
.notes-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.note-item {
  padding: 0.75rem;
  border-radius: 8px;
  cursor: pointer;
}
.note-item:hover {
  background: #f1f5f9;
}
.note-item.active {
  background: #eef2ff;
}
.note-title-input {
  width: 100%;
  font-size: 1.25rem;
  font-weight: 600;
  border: none;
  border-bottom: 2px solid #e2e8f0;
  padding: 0.5rem 0;
  margin-bottom: 1rem;
}
.note-body-input {
  width: 100%;
  min-height: 300px;
  border: none;
  resize: vertical;
  font-size: 1rem;
  line-height: 1.6;
}

/* Timer */
.timer-plugin {
  text-align: center;
  padding: 2rem;
}
.timer-display {
  font-size: 4rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
}
.timer-controls {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  margin-bottom: 2rem;
}
.lap-table {
  width: 100%;
  max-width: 400px;
  margin: 0 auto;
  border-collapse: collapse;
}
.lap-table th,
.lap-table td {
  padding: 0.5rem 1rem;
  text-align: right;
  border-bottom: 1px solid #e2e8f0;
}

/* Weather */
.weather-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 1rem;
}
.weather-card {
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: white;
  padding: 1.5rem;
  border-radius: 12px;
  text-align: center;
}
.weather-icon {
  font-size: 3rem;
  margin: 0.5rem 0;
}
.temperature {
  font-size: 2rem;
  font-weight: 700;
}

/* File Tree */
.file-tree {
  background: #1e1e2e;
  color: #d4d4d8;
  padding: 1rem;
  border-radius: 8px;
  font-family: 'SF Mono', monospace;
  font-size: 0.875rem;
}
.file-node {
  cursor: default;
}
.folder {
  cursor: pointer;
  padding: 0.25rem 0;
}
.folder:hover {
  background: #313244;
  border-radius: 4px;
}
.file {
  padding: 0.25rem 0;
  display: flex;
  gap: 0.5rem;
}
.file .size {
  margin-left: auto;
  color: #71717a;
}
.toggle {
  width: 1em;
  display: inline-block;
}

What This Demonstrates ​

  • Plugin architecture — runtime registration with registerPlugin()
  • Lazy loading — plugins loaded asynchronously on first activation
  • Template.dynamic — switching rendered template by name
  • Template.__define__ — registering templates at runtime
  • Recursive templates — file tree using self-referencing {{> fileNode}}
  • Cross-component communication — walking the view hierarchy to find parent state
  • Timer with cleanup — onDestroyed clears intervals
  • Computed depth — inline {{math depth "+" 1}} for recursive indentation

Released under the MIT License.

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