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

function useBatcher<TValue, TSelected>(
   fn, 
   options, 
selector): ReactBatcher<TValue, TSelected>;


function useBatcher<TValue, TSelected>(
   fn, 
   options, 
selector): ReactBatcher<TValue, TSelected>;

Defined in: react-pacer/src/batcher/useBatcher.ts:122

A React hook that creates and manages a Batcher instance.

This is a lower-level hook that provides direct access to the Batcher's functionality without any built-in state management. This allows you to integrate it with any state management solution you prefer (useState, Redux, Zustand, etc.) by utilizing the onItemsChange callback.

The Batcher collects items and processes them in batches based on configurable conditions:

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

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:

executionCount: Number of batch executions that have been completed
isEmpty: Whether the batcher has no items to process
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
size: Number of items currently in the batch queue
status: Current processing status ('idle' | 'pending')
totalItemsProcessed: Total number of items processed across all batches

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

TValue

### TSelected

TSelected = { }

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

(items) => void

### options

BatcherOptions<TValue> = {}

### selector

(state) => TSelected

Returns
-------

ReactBatcher <TValue, TSelected>

Example
-------

tsx

// Default behavior - no reactive state subscriptions
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 }
);

// Opt-in to re-render when batch size changes (optimized for displaying queue size)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    size: state.size,
    isEmpty: state.isEmpty
  })
);

// Opt-in to re-render when execution metrics change (optimized for stats display)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    executionCount: state.executionCount,
    totalItemsProcessed: state.totalItemsProcessed
  })
);

// Opt-in to re-render when processing state changes (optimized for loading indicators)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    isPending: state.isPending,
    isRunning: state.isRunning,
    status: state.status
  })
);

// Example with custom state management and batching
const [items, setItems] = useState([]);

const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  {
    maxSize: 5,
    wait: 2000,
    onItemsChange: (batcher) => setItems(batcher.peekAllItems()),
    getShouldExecute: (items) => items.length >= 3
  }
);

// Add items to batch - they'll be processed when conditions are met
batcher.addItem(1);
batcher.addItem(2);
batcher.addItem(3); // Triggers batch processing

// Control the batcher
batcher.stop();  // Pause batching
batcher.start(); // Resume batching

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


// Default behavior - no reactive state subscriptions
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 }
);

// Opt-in to re-render when batch size changes (optimized for displaying queue size)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    size: state.size,
    isEmpty: state.isEmpty
  })
);

// Opt-in to re-render when execution metrics change (optimized for stats display)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    executionCount: state.executionCount,
    totalItemsProcessed: state.totalItemsProcessed
  })
);

// Opt-in to re-render when processing state changes (optimized for loading indicators)
const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  { maxSize: 5, wait: 2000 },
  (state) => ({
    isPending: state.isPending,
    isRunning: state.isRunning,
    status: state.status
  })
);

// Example with custom state management and batching
const [items, setItems] = useState([]);

const batcher = useBatcher<number>(
  (items) => console.log('Processing batch:', items),
  {
    maxSize: 5,
    wait: 2000,
    onItemsChange: (batcher) => setItems(batcher.peekAllItems()),
    getShouldExecute: (items) => items.length >= 3
  }
);

// Add items to batch - they'll be processed when conditions are met
batcher.addItem(1);
batcher.addItem(2);
batcher.addItem(3); // Triggers batch processing

// Control the batcher
batcher.stop();  // Pause batching
batcher.start(); // Resume batching

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

Edit on GitHub

ReactAsyncBatcher

useAsyncBatcher

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