Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 4x 4x 4x 4x 4x 4x 4x 4x 4x 4x 2x 2x 4x 1x 1x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 4x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 17x 7x 7x 5x 4x 4x 5x 5x 1x 1x 1x 4x 4x 2x 7x 2x 7x 7x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 7x 17x 17x 17x 1x 1x 1x 1x 1x 1x 17x 17x 17x 17x 17x 17x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 2x 2x 1x 1x 1x 1x 1x 1x 2x 3x 2x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x | /**
* @fileoverview Component Lazy Loading with Intersection Observer
* Provides lazy loading capabilities for Coherent.js components
* @module @coherentjs/core/components/lazy-loading
*/
/**
* @typedef {Object} LazyLoadOptions
* @property {boolean} [enabled=true] - Enable lazy loading
* @property {string} [rootMargin='200px'] - Root margin for intersection observer
* @property {number} [threshold=0] - Intersection threshold (0.0 to 1.0)
* @property {Function} [placeholder] - Placeholder component function
* @property {string} [strategy='viewport'] - Loading strategy: 'viewport', 'eager', 'idle'
* @property {number} [delay=0] - Delay before loading (ms)
* @property {Function} [onLoad] - Callback when component loads
* @property {Function} [onError] - Callback when loading fails
* @property {boolean} [preload=false] - Preload on hover/focus
* @property {number} [preloadDelay=200] - Delay before preloading (ms)
* @property {boolean} [unloadOnHidden=false] - Unload when out of viewport
* @property {boolean} [retryOnError=true] - Retry loading on error
* @property {number} [maxRetries=3] - Maximum retry attempts
* @property {number} [retryDelay=1000] - Delay between retries (ms)
*/
/**
* @typedef {Object} LazyComponentState
* @property {'pending'|'loading'|'loaded'|'error'} status - Current loading status
* @property {Error|null} error - Error if loading failed
* @property {number} retries - Number of retry attempts
* @property {any} componentResult - Rendered component result
* @property {Function|null} cleanup - Cleanup function
*/
/**
* Default placeholder component
* @returns {Object} Placeholder component
*/
const defaultPlaceholder = () => ({
div: {
className: 'coherent-lazy-placeholder',
style: 'min-height: 100px; display: flex; align-items: center; justify-content: center;',
children: [
{
div: {
className: 'coherent-lazy-spinner',
text: 'Loading...'
}
}
]
}
});
/**
* Default error component
* @param {Error} error - The error that occurred
* @param {Function} retry - Retry function
* @returns {Object} Error component
*/
const defaultErrorComponent = (error, retry) => ({
div: {
className: 'coherent-lazy-error',
style: 'min-height: 100px; display: flex; flex-direction: column; align-items: center; justify-content: center; color: #d32f2f;',
children: [
{
p: {
text: 'Failed to load component'
}
},
{
p: {
style: 'font-size: 0.875rem; color: #666;',
text: error.message
}
},
{
button: {
text: 'Retry',
onclick: retry,
style: 'margin-top: 8px; padding: 8px 16px; cursor: pointer;'
}
}
]
}
});
/**
* Create a lazy-loaded component wrapper
* @param {Function|Promise<Function>} componentLoader - Component loader function
* @param {LazyLoadOptions} options - Lazy loading options
* @returns {Function} Lazy-loaded component wrapper
*/
export function createLazyComponent(componentLoader, options = {}) {
const opts = {
enabled: true,
rootMargin: '200px',
threshold: 0,
placeholder: defaultPlaceholder,
strategy: 'viewport',
delay: 0,
onLoad: null,
onError: null,
preload: false,
preloadDelay: 200,
unloadOnHidden: false,
retryOnError: true,
maxRetries: 3,
retryDelay: 1000,
errorComponent: defaultErrorComponent,
...options
};
// If lazy loading is disabled, return component directly
if (!opts.enabled) {
return async function LazyComponentEager(props) {
const component = typeof componentLoader === 'function'
? await componentLoader()
: await componentLoader;
return component(props);
};
}
/** @type {LazyComponentState} */
const state = {
status: 'pending',
error: null,
retries: 0,
componentResult: null,
cleanup: null
};
let observer = null;
let preloadTimeout = null;
let cachedComponent = null;
/**
* Load the component
* @param {any} props - Component props
* @returns {Promise<any>} Loaded component result
*/
async function loadComponent(props) {
if (state.status === 'loading') {
return state.componentResult;
}
if (state.status === 'loaded' && cachedComponent) {
return cachedComponent(props);
}
state.status = 'loading';
try {
// Add delay if specified
if (opts.delay > 0) {
await new Promise(resolve => setTimeout(resolve, opts.delay));
}
// Load the component
const component = typeof componentLoader === 'function'
? await componentLoader()
: await componentLoader;
cachedComponent = component;
state.status = 'loaded';
state.error = null;
state.retries = 0;
// Render component
const result = await component(props);
state.componentResult = result;
// Call onLoad callback
if (opts.onLoad) {
opts.onLoad(result);
}
return result;
} catch (error) {
state.status = 'error';
state.error = error;
// Call onError callback
if (opts.onError) {
opts.onError(error);
}
// Retry if enabled
if (opts.retryOnError && state.retries < opts.maxRetries) {
state.retries++;
await new Promise(resolve => setTimeout(resolve, opts.retryDelay));
return loadComponent(props);
}
throw error;
}
}
/**
* Setup intersection observer for viewport strategy
* @param {HTMLElement} element - Element to observe
* @param {any} props - Component props
*/
function setupViewportObserver(element, props) {
if (typeof IntersectionObserver === 'undefined') {
// Fallback: load immediately if IntersectionObserver not supported
loadComponent(props);
return;
}
observer = new IntersectionObserver(
(entries) => {
entries.forEach((entry) => {
if (entry.isIntersecting && state.status === 'pending') {
loadComponent(props).then((result) => {
if (element && element.parentNode) {
// Replace placeholder with loaded component
const tempDiv = document.createElement('div');
tempDiv.innerHTML = renderComponentToHTML(result);
const newElement = tempDiv.firstElementChild;
if (newElement) {
element.parentNode.replaceChild(newElement, element);
}
}
}).catch((error) => {
console.error('Failed to load lazy component:', error);
if (element && element.parentNode) {
// Show error component
const tempDiv = document.createElement('div');
tempDiv.innerHTML = renderComponentToHTML(opts.errorComponent(error, () => {
state.status = 'pending';
state.retries = 0;
setupViewportObserver(element, props);
}));
const errorElement = tempDiv.firstElementChild;
if (errorElement) {
element.parentNode.replaceChild(errorElement, element);
}
}
});
observer.disconnect();
} else if (!entry.isIntersecting && opts.unloadOnHidden && state.status === 'loaded') {
// Unload component when out of viewport
if (state.cleanup) {
state.cleanup();
}
state.status = 'pending';
cachedComponent = null;
}
});
},
{
rootMargin: opts.rootMargin,
threshold: opts.threshold
}
);
observer.observe(element);
}
/**
* Setup preloading on hover/focus
* @param {HTMLElement} element - Element to attach listeners
* @param {any} props - Component props
*/
function setupPreload(element, props) {
if (!opts.preload) return;
const preloadHandler = () => {
if (state.status === 'pending') {
clearTimeout(preloadTimeout);
preloadTimeout = setTimeout(() => {
loadComponent(props);
}, opts.preloadDelay);
}
};
element.addEventListener('mouseenter', preloadHandler);
element.addEventListener('focus', preloadHandler);
// Store cleanup function
state.cleanup = () => {
clearTimeout(preloadTimeout);
element.removeEventListener('mouseenter', preloadHandler);
element.removeEventListener('focus', preloadHandler);
if (observer) {
observer.disconnect();
}
};
}
/**
* Lazy component wrapper function
* @param {any} props - Component props
* @returns {Object} Component result (placeholder, loaded, or error)
*/
function LazyComponentWrapper(props) {
// Strategy: eager - load immediately
if (opts.strategy === 'eager') {
if (state.status === 'pending') {
loadComponent(props).catch(() => {});
}
if (state.status === 'loaded') {
return state.componentResult || cachedComponent(props);
} else if (state.status === 'error') {
return opts.errorComponent(state.error, () => {
state.status = 'pending';
state.retries = 0;
return LazyComponentWrapper(props);
});
}
return opts.placeholder(props);
}
// Strategy: idle - load when browser is idle
if (opts.strategy === 'idle') {
if (state.status === 'pending') {
if (typeof requestIdleCallback !== 'undefined') {
requestIdleCallback(() => loadComponent(props).catch(() => {}));
} else {
setTimeout(() => loadComponent(props).catch(() => {}), 1);
}
}
if (state.status === 'loaded') {
return state.componentResult || cachedComponent(props);
} else if (state.status === 'error') {
return opts.errorComponent(state.error, () => {
state.status = 'pending';
state.retries = 0;
return LazyComponentWrapper(props);
});
}
return opts.placeholder(props);
}
// Strategy: viewport - load when in viewport (default)
if (state.status === 'loaded') {
return state.componentResult || cachedComponent(props);
} else if (state.status === 'error') {
return opts.errorComponent(state.error, () => {
state.status = 'pending';
state.retries = 0;
return LazyComponentWrapper(props);
});
}
// Return placeholder with data attribute for hydration
const placeholder = opts.placeholder(props);
// Add lazy loading marker
return {
...placeholder,
[Object.keys(placeholder)[0]]: {
...placeholder[Object.keys(placeholder)[0]],
'data-lazy-loading': 'true',
'data-lazy-id': `lazy-${Math.random().toString(36).substring(2, 11)}`
}
};
}
// Expose methods for manual control
LazyComponentWrapper.load = (props) => loadComponent(props);
LazyComponentWrapper.reset = () => {
state.status = 'pending';
state.error = null;
state.retries = 0;
state.componentResult = null;
cachedComponent = null;
if (state.cleanup) {
state.cleanup();
}
};
LazyComponentWrapper.getState = () => ({ ...state });
LazyComponentWrapper.setupViewportObserver = setupViewportObserver;
LazyComponentWrapper.setupPreload = setupPreload;
return LazyComponentWrapper;
}
/**
* Simple HTML renderer helper (basic implementation)
* @param {Object} component - Component to render
* @returns {string} HTML string
*/
function renderComponentToHTML(component) {
if (!component || typeof component !== 'object') {
return String(component || '');
}
const tag = Object.keys(component)[0];
const props = component[tag];
if (!props) {
return `<${tag}></${tag}>`;
}
const attributes = [];
let content = '';
Object.entries(props).forEach(([key, value]) => {
if (key === 'children') {
content = Array.isArray(value)
? value.map(child => renderComponentToHTML(child)).join('')
: renderComponentToHTML(value);
} else if (key === 'text') {
content = escapeHTML(String(value));
} else if (key === 'html') {
content = String(value);
} else if (key !== 'onclick' && key !== 'onload' && !key.startsWith('on')) {
attributes.push(`${key}="${escapeHTML(String(value))}"`);
}
});
const attrsStr = attributes.length > 0 ? ` ${ attributes.join(' ')}` : '';
return `<${tag}${attrsStr}>${content}</${tag}>`;
}
/**
* Escape HTML special characters
* @param {string} str - String to escape
* @returns {string} Escaped string
*/
function escapeHTML(str) {
return str
.replace(/&/g, '&')
.replace(/</g, '<')
.replace(/>/g, '>')
.replace(/"/g, '"')
.replace(/'/g, ''');
}
/**
* Initialize lazy loading for all components with data-lazy-loading attribute
* Call this after hydration
*/
export function initializeLazyLoading() {
if (typeof document === 'undefined') {
return;
}
const lazyElements = document.querySelectorAll('[data-lazy-loading="true"]');
lazyElements.forEach((element) => {
const lazyId = element.getAttribute('data-lazy-id');
// Setup intersection observer for this element
if (typeof IntersectionObserver !== 'undefined') {
const observer = new IntersectionObserver(
(entries) => {
entries.forEach((entry) => {
if (entry.isIntersecting) {
// Trigger lazy load event
element.dispatchEvent(new CustomEvent('lazy-load', {
detail: { lazyId }
}));
observer.disconnect();
}
});
},
{
rootMargin: '200px',
threshold: 0
}
);
observer.observe(element);
}
});
}
/**
* Higher-order component for lazy loading
* @param {Function} Component - Component to wrap
* @param {LazyLoadOptions} options - Lazy loading options
* @returns {Function} Lazy-loaded component
*/
export function withLazyLoading(Component, options = {}) {
return createLazyComponent(() => Promise.resolve(Component), options);
}
/**
* Batch lazy load multiple components
* @param {Array<{loader: Function, options?: LazyLoadOptions}>} components - Components to lazy load
* @returns {Array<Function>} Array of lazy-loaded components
*/
export function batchLazyLoad(components) {
return components.map(({ loader, options = {} }) =>
createLazyComponent(loader, options)
);
}
/**
* Preload a component without rendering it
* @param {Function|Promise<Function>} componentLoader - Component loader
* @returns {Promise<Function>} Loaded component
*/
export async function preloadComponent(componentLoader) {
const component = typeof componentLoader === 'function'
? await componentLoader()
: await componentLoader;
return component;
}
export default {
createLazyComponent,
withLazyLoading,
batchLazyLoad,
preloadComponent,
initializeLazyLoading
};
|