Function: useAsyncRateLimiter()

function useAsyncRateLimiter<TFn, TSelected>( fn, options, selector): ReactAsyncRateLimiter<TFn, TSelected>;

function useAsyncRateLimiter<TFn, TSelected>( fn, options, selector): ReactAsyncRateLimiter<TFn, TSelected>;

Defined in: react-pacer/src/async-rate-limiter/useAsyncRateLimiter.ts:179

A low-level React hook that creates an AsyncRateLimiter instance to limit how many times an async function can execute within a time window.

This hook is designed to be flexible and state-management agnostic - it simply returns a rate limiter instance that you can integrate with any state management solution (useState, Redux, Zustand, Jotai, etc).

Rate limiting allows an async function to execute up to a specified limit within a time window, then blocks subsequent calls until the window passes. This is useful for respecting API rate limits, managing resource constraints, or controlling bursts of async operations.

Unlike the non-async RateLimiter, this async version supports returning values from the rate-limited function, making it ideal for API calls and other async operations where you want the result of the maybeExecute call instead of setting the result on a state variable from within the rate-limited function.

The rate limiter supports two types of windows:

'fixed': A strict window that resets after the window period. All executions within the window count towards the limit, and the window resets completely after the period.
'sliding': A rolling window that allows executions as old ones expire. This provides a more consistent rate of execution over time.

Error Handling:

If an onError handler is provided, it will be called with the error and rate limiter 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 AsyncRateLimiter instance
Rate limit rejections (when limit is exceeded) are handled separately from execution errors via the onReject handler

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 function executions that have resulted in errors
executionTimes: Array of timestamps when executions occurred for rate limiting calculations
isExecuting: Whether the rate-limited function is currently executing asynchronously
lastResult: The result from the most recent successful function execution
rejectionCount: Number of function executions that have been rejected due to rate limiting
settleCount: Number of function executions that have completed (success or error)
successCount: Number of function executions that have completed successfully

// Default behavior - no reactive state subscriptions const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; // Return value is preserved }, { limit: 5, window: 1000 } // 5 calls per second ); // Opt-in to re-render when execution state changes (optimized for loading indicators) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ isExecuting: state.isExecuting }) ); // Opt-in to re-render when results are available (optimized for data display) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ lastResult: state.lastResult, successCount: state.successCount }) ); // Opt-in to re-render when error/rejection state changes (optimized for error handling) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000, onError: (error) => console.error('API call failed:', error), onReject: (rateLimiter) => console.log('Rate limit exceeded') }, (state) => ({ errorCount: state.errorCount, rejectionCount: state.rejectionCount }) ); // Opt-in to re-render when execution metrics change (optimized for stats display) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ successCount: state.successCount, errorCount: state.errorCount, settleCount: state.settleCount, rejectionCount: state.rejectionCount }) ); // Opt-in to re-render when execution times change (optimized for window calculations) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ executionTimes: state.executionTimes }) ); // With state management and return value const [data, setData] = useState(null); const { maybeExecute, state } = useAsyncRateLimiter( async (query) => { const result = await searchAPI(query); setData(result); return result; // Return value can be used by the caller }, { limit: 10, window: 60000, // 10 calls per minute onReject: (rateLimiter) => { console.log(`Rate limit exceeded. Try again in ${rateLimiter.getMsUntilNextWindow()}ms`); }, onError: (error) => { console.error('API call failed:', error); } } ); // Access the selected state (will be empty object {} unless selector provided) const { isExecuting, lastResult, rejectionCount } = state;

// Default behavior - no reactive state subscriptions const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; // Return value is preserved }, { limit: 5, window: 1000 } // 5 calls per second ); // Opt-in to re-render when execution state changes (optimized for loading indicators) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ isExecuting: state.isExecuting }) ); // Opt-in to re-render when results are available (optimized for data display) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ lastResult: state.lastResult, successCount: state.successCount }) ); // Opt-in to re-render when error/rejection state changes (optimized for error handling) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000, onError: (error) => console.error('API call failed:', error), onReject: (rateLimiter) => console.log('Rate limit exceeded') }, (state) => ({ errorCount: state.errorCount, rejectionCount: state.rejectionCount }) ); // Opt-in to re-render when execution metrics change (optimized for stats display) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ successCount: state.successCount, errorCount: state.errorCount, settleCount: state.settleCount, rejectionCount: state.rejectionCount }) ); // Opt-in to re-render when execution times change (optimized for window calculations) const asyncRateLimiter = useAsyncRateLimiter( async (id: string) => { const data = await api.fetchData(id); return data; }, { limit: 5, window: 1000 }, (state) => ({ executionTimes: state.executionTimes }) ); // With state management and return value const [data, setData] = useState(null); const { maybeExecute, state } = useAsyncRateLimiter( async (query) => { const result = await searchAPI(query); setData(result); return result; // Return value can be used by the caller }, { limit: 10, window: 60000, // 10 calls per minute onReject: (rateLimiter) => { console.log(`Rate limit exceeded. Try again in ${rateLimiter.getMsUntilNextWindow()}ms`); }, onError: (error) => { console.error('API call failed:', error); } } ); // Access the selected state (will be empty object {} unless selector provided) const { isExecuting, lastResult, rejectionCount } = state;

useAsyncRateLimiter

Function: useAsyncRateLimiter()

State Management and Selector

Type Parameters

TFn

TSelected

Parameters

fn

options

selector

Returns

Example