@lamlib/data-sync

A lightweight client-side data synchronization library built on the Fetch API. Simplify your HTTP requests with endpoint registration, automatic caching, loading state management, and request interceptors.

Installation

NPM

npm install @lamlib/data-sync

CDN (Browser)

ES Module:

<script type="module">
  import {
    registerGetEndpoint,
    registerPostEndpoint,
    requestHandlers
  } from 'https://unpkg.com/@lamlib/data-sync/lib/datasync.esm.js';

  // Your code here
</script>

IIFE (Global variable):

<script src="https://unpkg.com/@lamlib/data-sync/lib/datasync.iife.js"></script>
<script>
  const {
    registerGetEndpoint,
    registerPostEndpoint,
    requestHandlers
  } = DataSync;

  // Your code here
</script>

jsDelivr alternative:

<!-- ESM -->
<script type="module">
  import { ... } from 'https://cdn.jsdelivr.net/npm/@lamlib/data-sync/lib/datasync.esm.js';
</script>

<!-- IIFE -->
<script src="https://cdn.jsdelivr.net/npm/@lamlib/data-sync/lib/datasync.iife.js"></script>

Quick Start

import {
  registerGetEndpoint,
  registerPostEndpoint,
  requestHandlers,
  setLoadingHooks
} from '@lamlib/data-sync';

// 1. Set up loading hooks (optional)
setLoadingHooks({
  onQueueAdd: () => showSpinner(),
  onQueueEmpty: () => hideSpinner()
});

// 2. Register your endpoints
registerGetEndpoint('getUsers', '/api/users');
registerPostEndpoint('createUser', '/api/users');

// 3. Make requests
const users = await requestHandlers.getUsers();
const newUser = await requestHandlers.createUser({ name: 'John', email: 'john@example.com' });

Features

• Endpoint Registration - Register GET, POST, PUT, PATCH, DELETE endpoints once, use anywhere
• Automatic Caching - GET requests are cached based on parameters to avoid duplicate calls
• Path Parameters - Support for dynamic URL segments (e.g., /api/users/:id)
• Loading State Management - Built-in hooks for handling loading UI states
• Request Interceptors - Modify requests before they're sent and handle responses
• FormData Support - Automatic handling of FormData for file uploads
• Error Handling - Centralized error catching and message state management

API Reference

Endpoint Registration

registerGetEndpoint(name, url, mode?)

Register a GET endpoint.

Parameter	Type	Description
name	string	Unique identifier for the endpoint
url	string	URL endpoint (supports path params like /api/users/:id)
mode	'no-cache'	Optional. If set, bypasses caching

// Basic usage
registerGetEndpoint('getUsers', '/api/users');

// With path parameters
registerGetEndpoint('getUser', '/api/users/:id');

// Without caching
registerGetEndpoint('getLatestData', '/api/data', 'no-cache');

// Call the endpoint
const users = await requestHandlers.getUsers();
const user = await requestHandlers.getUser({ id: 123 });
const data = await requestHandlers.getLatestData({ filter: 'active' });

registerPostEndpoint(name, url)

Register a POST endpoint.

Signature: requestHandlers.name(body, params)

Parameter	Type	Description
body	object | FormData	Request body (JSON or FormData)
params	object	Optional. Path params and query params

registerPostEndpoint('createUser', '/api/users');
registerPostEndpoint('updateUserStatus', '/api/users/:id/status');
registerPostEndpoint('addComment', '/api/posts/:postId/comments');

// 1. Call with body only
await requestHandlers.createUser({ name: 'John', email: 'john@example.com' });

// 2. Call with body + path params
// URL: /api/users/123/status
await requestHandlers.updateUserStatus(
  { status: 'active' },           // body - sent as JSON
  { id: 123 }                     // params - :id becomes path param
);

// 3. Call with body + path params + query params
// URL: /api/posts/456/comments?notify=true&lang=en
await requestHandlers.addComment(
  { content: 'Great post!' },     // body - sent as JSON
  {
    postId: 456,                  // path param - replaces :postId
    notify: true,                 // query param - added to URL
    lang: 'en'                    // query param - added to URL
  }
);

// 4. Call with FormData for file uploads
const formData = new FormData();
formData.append('file', fileInput.files[0]);
formData.append('description', 'My photo');
await requestHandlers.createUser(formData);

// 5. FormData with path params
// URL: /api/posts/789/comments
const formData2 = new FormData();
formData2.append('image', imageFile);
await requestHandlers.addComment(formData2, { postId: 789 });

How params work:

• Path params (e.g., :id, :postId) are replaced in the URL
• Remaining params are converted to query string
• Example: { postId: 456, notify: true } with URL /api/posts/:postId/comments
  • :postId → 456 (path param)
  • notify=true → query string

registerPutEndpoint(name, url)

Register a PUT endpoint.

registerPutEndpoint('updateUser', '/api/users/:id');

await requestHandlers.updateUser(
  { name: 'John Doe', email: 'john.doe@example.com' },
  { id: 123 }
);

registerPatchEndpoint(name, url)

Register a PATCH endpoint.

registerPatchEndpoint('patchUser', '/api/users/:id');

await requestHandlers.patchUser({ name: 'Jane' }, { id: 123 });

registerDeleteEndpoint(name, url)

Register a DELETE endpoint.

registerDeleteEndpoint('deleteUser', '/api/users/:id');

await requestHandlers.deleteUser({ id: 123 });

---

Loading Hooks

setLoadingHooks({ onQueueAdd, onQueueEmpty })

Set callbacks for loading state management. Loading UI is triggered after a 600ms delay to avoid flickering on fast requests.

setLoadingHooks({
  onQueueAdd: () => {
    document.getElementById('spinner').style.display = 'block';
  },
  onQueueEmpty: () => {
    document.getElementById('spinner').style.display = 'none';
  }
});

---

Response Operators

setResponseOperator({ picker, errCatcher })

Customize how responses are processed.

Parameter	Type	Description
picker	(result) => any	Extract data from response
errCatcher	(response, result) => void	Handle errors (throw to trigger error state)

import { setResponseOperator } from '@lamlib/data-sync';

setResponseOperator({
  // Custom data extraction
  picker: (result) => result.payload,

  // Custom error handling
  errCatcher: (response, result) => {
    if (!response.ok || result.error) {
      throw new Error(result.error?.message || 'Request failed');
    }
  }
});

Default behavior:

• picker: Returns result.data or result.result
• errCatcher: Throws error if result.code !== 'SUCCESS', result.result === false, or !response.ok

resetResponseOperator()

Reset response operators to default behavior.

import { resetResponseOperator } from '@lamlib/data-sync';

resetResponseOperator();

---

Interceptors

interceptors.before

Execute logic before each request. Useful for adding authentication headers.

import { interceptors } from '@lamlib/data-sync';

interceptors.before = async ({ params, body, headers, type }) => {
  // Add auth token to all requests
  const token = localStorage.getItem('token');
  if (token) {
    headers.append('Authorization', `Bearer ${token}`);
  }

  // Log request type
  console.log(`Making ${type} request`);
};

interceptors.after

Execute logic after each successful response.

interceptors.after = (result) => {
  // Log all responses
  console.log('Response received:', result);

  // Handle token refresh
  if (result.newToken) {
    localStorage.setItem('token', result.newToken);
  }
};

---

State Management

dataStore

A Map containing synced data from the server, keyed by endpoint name.

import { dataStore, requestHandlers } from '@lamlib/data-sync';

await requestHandlers.getUsers();
const users = dataStore.get('getUsers');

paramCache

A Map containing cached parameters to prevent duplicate requests.

import { paramCache } from '@lamlib/data-sync';

// Check cached params for an endpoint
const cachedParams = paramCache.get('getUsers');

messageState

Object containing error and success messages from the last request.

import { messageState, requestHandlers } from '@lamlib/data-sync';

await requestHandlers.createUser({ name: 'John' });

if (messageState.error) {
  console.error('Error:', messageState.error.message);
} else if (messageState.success) {
  console.log('Success:', messageState.success);
}

hasError()

Check if an error occurred in the last request.

import { hasError, messageState } from '@lamlib/data-sync';

await requestHandlers.createUser({ name: 'John' });

if (hasError()) {
  alert(messageState.error.message);
}

---

Complete Example

import {
  registerGetEndpoint,
  registerPostEndpoint,
  registerPutEndpoint,
  registerDeleteEndpoint,
  setLoadingHooks,
  setResponseOperator,
  interceptors,
  requestHandlers,
  messageState,
  hasError
} from '@lamlib/data-sync';

// Configure loading UI
setLoadingHooks({
  onQueueAdd: () => document.body.classList.add('loading'),
  onQueueEmpty: () => document.body.classList.remove('loading')
});

setLoadingDelay({
  queueAddDelay: 10, //ms
  queueEmptyDelay: 500, //ms
})

// Configure response handling for your API format
setResponseOperator({
  picker: (result) => result.data,
  errCatcher: (response, result) => {
    if (!response.ok) throw new Error(result.message || 'Request failed');
  }
});

// Add authentication to all requests
interceptors.before = async ({ headers }) => {
  const token = localStorage.getItem('authToken');
  if (token) {
    headers.append('Authorization', `Bearer ${token}`);
  }
};

// Register all endpoints
registerGetEndpoint('getUsers', '/api/users');
registerGetEndpoint('getUser', '/api/users/:id');
registerPostEndpoint('createUser', '/api/users');
registerPutEndpoint('updateUser', '/api/users/:id');
registerDeleteEndpoint('deleteUser', '/api/users/:id');

// Usage in your application
async function loadUsers() {
  const users = await requestHandlers.getUsers();
  if (!hasError()) {
    renderUserList(users);
  }
}

async function createUser(userData) {
  await requestHandlers.createUser(userData);
  if (hasError()) {
    showError(messageState.error.message);
  } else {
    showSuccess(messageState.success);
    loadUsers(); // Refresh list
  }
}

async function updateUser(id, userData) {
  await requestHandlers.updateUser(userData, { id });
  if (!hasError()) {
    loadUsers();
  }
}

async function deleteUser(id) {
  await requestHandlers.deleteUser({ id });
  if (!hasError()) {
    loadUsers();
  }
}

License

ISC