📄 tanstack/pacer/latest/docs/framework/react/reference/functions/useAsyncBatcher

function useAsyncBatcher<TValue, TSelected>(
   fn, 
   options, 
selector): ReactAsyncBatcher<TValue, TSelected>;


function useAsyncBatcher<TValue, TSelected>(
   fn, 
   options, 
selector): ReactAsyncBatcher<TValue, TSelected>;

Defined in: react-pacer/src/async-batcher/useAsyncBatcher.ts:168

A React hook that creates an AsyncBatcher instance for managing asynchronous batches of items.

This is the async version of the useBatcher hook. Unlike the sync version, this async batcher:

Handles promises and returns results from batch executions
Provides error handling with configurable error behavior
Tracks success, error, and settle counts separately
Has state tracking for when batches are executing
Returns the result of the batch function execution

Features:

Configurable batch size and wait time
Custom batch processing logic via getShouldExecute
Event callbacks for monitoring batch operations
Error handling for failed batch operations
Automatic or manual batch processing

The batcher collects items and processes them in batches based on:

Maximum batch size (number of items per batch)
Time-based batching (process after X milliseconds)
Custom batch processing logic via getShouldExecute

Error Handling:

If an onError handler is provided, it will be called with the error and batcher instance
If throwOnError is true (default when no onError handler is provided), the error will be thrown
If throwOnError is false (default when onError handler is provided), the error will be swallowed
Both onError and throwOnError can be used together - the handler will be called before any error is thrown
The error state can be checked using the underlying AsyncBatcher instance

State Management and Selector
-----------------------------

The hook uses TanStack Store for reactive state management. The selector parameter allows you to specify which state changes will trigger a re-render, optimizing performance by preventing unnecessary re-renders when irrelevant state changes occur.

By default, there will be no reactive state subscriptions and you must opt-in to state tracking by providing a selector function. This prevents unnecessary re-renders and gives you full control over when your component updates. Only when you provide a selector will the component re-render when the selected state values change.

Available state properties:

errorCount: Number of batch executions that have resulted in errors
failedItems: Array of items that failed during batch processing
isEmpty: Whether the batcher has no items to process
isExecuting: Whether a batch is currently being processed asynchronously
isPending: Whether the batcher is waiting for the timeout to trigger batch processing
isRunning: Whether the batcher is active and will process items automatically
items: Array of items currently queued for batch processing
lastResult: The result from the most recent batch execution
settleCount: Number of batch executions that have completed (success or error)
size: Number of items currently in the batch queue
status: Current processing status ('idle' | 'pending' | 'executing' | 'populated')
successCount: Number of batch executions that have completed successfully
totalItemsProcessed: Total number of items processed across all batches
totalItemsFailed: Total number of items that have failed processing

Type Parameters
--------------- ### TValue

TValue

### TSelected

TSelected = { }

Parameters
---------- ### fn

(items) => Promise<any>

### options

AsyncBatcherOptions<TValue> = {}

### selector

(state) => TSelected

Returns
-------

ReactAsyncBatcher <TValue, TSelected>

Example
-------

tsx

// Basic async batcher for API requests - no reactive state subscriptions
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 }
);

// Opt-in to re-render when execution state changes (optimized for loading indicators)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 },
  (state) => ({
    isExecuting: state.isExecuting,
    isPending: state.isPending,
    status: state.status
  })
);

// Opt-in to re-render when results are available (optimized for data display)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 },
  (state) => ({
    lastResult: state.lastResult,
    successCount: state.successCount,
    totalItemsProcessed: state.totalItemsProcessed
  })
);

// Opt-in to re-render when error state changes (optimized for error handling)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  {
    maxSize: 10,
    wait: 2000,
    onError: (error) => console.error('Batch processing failed:', error)
  },
  (state) => ({
    errorCount: state.errorCount,
    failedItems: state.failedItems,
    totalItemsFailed: state.totalItemsFailed
  })
);

// Complete example with all callbacks
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  {
    maxSize: 10,
    wait: 2000,
    onSuccess: (result) => {
      console.log('Batch processed successfully:', result);
    },
    onError: (error) => {
      console.error('Batch processing failed:', error);
    }
  }
);

// Add items to batch
asyncBatcher.addItem(newItem);

// Manually execute batch
const result = await asyncBatcher.execute();

// Access the selected state (will be empty object {} unless selector provided)
const { isExecuting, lastResult, size } = asyncBatcher.state;


// Basic async batcher for API requests - no reactive state subscriptions
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 }
);

// Opt-in to re-render when execution state changes (optimized for loading indicators)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 },
  (state) => ({
    isExecuting: state.isExecuting,
    isPending: state.isPending,
    status: state.status
  })
);

// Opt-in to re-render when results are available (optimized for data display)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  { maxSize: 10, wait: 2000 },
  (state) => ({
    lastResult: state.lastResult,
    successCount: state.successCount,
    totalItemsProcessed: state.totalItemsProcessed
  })
);

// Opt-in to re-render when error state changes (optimized for error handling)
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  {
    maxSize: 10,
    wait: 2000,
    onError: (error) => console.error('Batch processing failed:', error)
  },
  (state) => ({
    errorCount: state.errorCount,
    failedItems: state.failedItems,
    totalItemsFailed: state.totalItemsFailed
  })
);

// Complete example with all callbacks
const asyncBatcher = useAsyncBatcher(
  async (items) => {
    const results = await Promise.all(items.map(item => processItem(item)));
    return results;
  },
  {
    maxSize: 10,
    wait: 2000,
    onSuccess: (result) => {
      console.log('Batch processed successfully:', result);
    },
    onError: (error) => {
      console.error('Batch processing failed:', error);
    }
  }
);

// Add items to batch
asyncBatcher.addItem(newItem);

// Manually execute batch
const result = await asyncBatcher.execute();

// Access the selected state (will be empty object {} unless selector provided)
const { isExecuting, lastResult, size } = asyncBatcher.state;

Edit on GitHub

useBatcher

useBatchedCallback

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