useBatcher | TanStack Pacer Русский

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

Defined in: batcher/useBatcher.ts:181

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. You can subscribe to state changes in two ways:

1. Using batcher.Subscribe HOC (Recommended for component tree subscriptions)

Use the Subscribe HOC to subscribe to state changes deep in your component tree without needing to pass a selector to the hook. This is ideal when you want to subscribe to state in child components.

2. Using the selector parameter (For hook-level subscriptions)

The selector parameter allows you to specify which state changes will trigger a re-render at the hook level, 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 or using the Subscribe HOC. This prevents unnecessary re-renders and gives you full control over when your component updates.

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
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

Unmount behavior

By default, the hook cancels any pending batch when the component unmounts. Use the onUnmount option to customize this. For example, to flush pending work instead:

const batcher = useBatcher(fn, {
  maxSize: 5,
  wait: 2000,
  onUnmount: (b) => b.flush()
});

Type Parameters

TValue

TValue

TSelected

TSelected = { }

Parameters

fn

(items) => void

options?

ReactBatcherOptions<TValue, TSelected> = {}

selector?

(state) => TSelected

Returns

ReactBatcher<TValue, TSelected>

Example

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

// Subscribe to state changes deep in component tree using Subscribe HOC
<batcher.Subscribe selector={(state) => ({ size: state.size, isPending: state.isPending })}>
  {({ size, isPending }) => (
    <div>Batch: {size} items, {isPending ? 'Pending' : 'Ready'}</div>
  )}
</batcher.Subscribe>

// Opt-in to re-render when batch size changes at hook level (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,
    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.cancel(); // Cancel the pending timer; queued items are retained
batcher.flush();  // Process queued items immediately

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