useQueuedState

Function: useQueuedState()

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

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

Defined in: react-pacer/src/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')

// 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;

// 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;

useQueuedState

Function: useQueuedState()

State Management and Selector

Type Parameters

Parameters

fn

options

selector?

Returns

Example

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