useQueuedState

function useQueuedState<TValue, TSelected>(
   fn,
   options?,
   selector?): [TValue[], (item, position?, runOnItemsChange?) => boolean, ReactQueuer<TValue, TSelected>];

Defined in: queuer/useQueuedState.ts:119

A React hook that creates a queuer with managed state, combining React's useState with queuing functionality. This hook provides both the current queue state and queue control methods.

The queue state is automatically updated whenever items are added, removed, or reordered in the queue. All queue operations are reflected in the state array returned by the hook.

The queue can be started and stopped to automatically process items at a specified interval, making it useful as a scheduler. When started, it will process one item per tick, with an optional wait time between ticks.

The hook returns a tuple containing:

• The current queue state as an array
• The queue instance with methods for queue manipulation

State Management and Selector

The hook uses TanStack Store for reactive state management via the underlying queuer instance. The selector parameter allows you to specify which queuer 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 queuer state properties:

• executionCount: Number of items that have been processed by the queuer
• expirationCount: Number of items that have been removed due to expiration
• isEmpty: Whether the queuer has no items to process
• isFull: Whether the queuer has reached its maximum capacity
• isIdle: Whether the queuer is not currently processing any items
• isRunning: Whether the queuer is active and will process items automatically
• items: Array of items currently waiting to be processed
• itemTimestamps: Timestamps when items were added for expiration tracking
• pendingTick: Whether the queuer has a pending timeout for processing the next item
• rejectionCount: Number of items that have been rejected from being added
• size: Number of items currently in the queue
• status: Current processing status ('idle' | 'running' | 'stopped')

Type Parameters

TValue

TValue

TSelected

TSelected extends Pick<QueuerState<TValue>, "items"> = Pick<QueuerState<TValue>, "items">

Parameters

fn

(item) => void

options?

ReactQueuerOptions<TValue, TSelected> = {}

selector?

(state) => TSelected

Returns

[TValue[], (item, position?, runOnItemsChange?) => boolean, ReactQueuer<TValue, TSelected>]

Example

// Default behavior - no reactive state subscriptions
const [items, addItem, queue] = useQueuedState(
  (item) => console.log('Processing:', item),
  {
    initialItems: ['item1', 'item2'],
    started: true,
    wait: 1000,
    getPriority: (item) => item.priority
  }
);

// Opt-in to re-render when queue contents change (optimized for displaying queue items)
const [items, addItem, queue] = useQueuedState(
  (item) => console.log('Processing:', item),
  { started: true, wait: 1000 },
  (state) => ({
    items: state.items,
    size: state.size,
    isEmpty: state.isEmpty
  })
);

// Opt-in to re-render when processing state changes (optimized for loading indicators)
const [items, addItem, queue] = useQueuedState(
  (item) => console.log('Processing:', item),
  { started: true, wait: 1000 },
  (state) => ({
    isRunning: state.isRunning,
    isIdle: state.isIdle,
    status: state.status,
    pendingTick: state.pendingTick
  })
);

// Opt-in to re-render when execution metrics change (optimized for stats display)
const [items, addItem, queue] = useQueuedState(
  (item) => console.log('Processing:', item),
  { started: true, wait: 1000 },
  (state) => ({
    executionCount: state.executionCount,
    expirationCount: state.expirationCount,
    rejectionCount: state.rejectionCount
  })
);

// Add items to queue
const handleAdd = (item) => {
  addItem(item);
};

// Start automatic processing
const startProcessing = () => {
  queue.start();
};

// Stop automatic processing
const stopProcessing = () => {
  queue.stop();
};

// Manual processing still available
const handleProcess = () => {
  const nextItem = queue.getNextItem();
  if (nextItem) {
    processItem(nextItem);
  }
};

// Access the selected queuer state (will be empty object {} unless selector provided)
const { size, isRunning, executionCount } = queue.state;