📄 tanstack/pacer/latest/docs/framework/react/examples/useAsyncThrottler

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tsx

import { useState } from 'react'
import ReactDOM from 'react-dom/client'
import { useAsyncThrottler } from '@tanstack/react-pacer/async-throttler'
import { PacerProvider } from '@tanstack/react-pacer/provider'

interface SearchResult {
  id: number
  title: string
}

// Simulate API call with fake data
const fakeApi = async (term: string): Promise<Array<SearchResult>> => {
  await new Promise((resolve) => setTimeout(resolve, 500)) // Simulate network delay
  return [\
    { id: 1, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
    { id: 2, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
    { id: 3, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
  ]
}

function App() {
  const [searchTerm, setSearchTerm] = useState('')
  const [results, setResults] = useState<Array<SearchResult>>([])
  const [error, setError] = useState<Error | null>(null)

  // The function that will become throttled
  const handleSearch = async (term: string) => {
    if (!term) {
      setResults([])
      return
    }

    // throw new Error('Test error') // you don't have to catch errors here (though you still can). The onError optional handler will catch it

    const data = await fakeApi(term)
    setResults(data)
    setError(null)

    return data // this could alternatively be a void function without a return
  }

  // hook that gives you an async throttler instance
  const setSearchAsyncThrottler = useAsyncThrottler(
    handleSearch,
    {
      // leading: true, // default
      // trailing: true, // default
      wait: 1000, // Wait 1 second between API calls
      onError: (error) => {
        // optional error handler
        console.error('Search failed:', error)
        setError(error as Error)
        setResults([])
      },
      // throwOnError: true,
    },
    // Optional Selector function to pick the state you want to track and use
    (state) => state,
  )

  // get and name our throttled function
  const handleSearchThrottled = setSearchAsyncThrottler.maybeExecute

  // instant event handler that calls both the instant local state setter and the throttled function
  async function onSearchChange(e: React.ChangeEvent<HTMLInputElement>) {
    const newTerm = e.target.value
    setSearchTerm(newTerm)
    const result = await handleSearchThrottled(newTerm) // optionally await if you need to
    console.log('result', result)
  }

  return (
    <div>
      <h1>TanStack Pacer useAsyncThrottler Example</h1>
      <div>
        <input
          autoFocus
          type="search"
          value={searchTerm}
          onChange={onSearchChange}
          placeholder="Type to search..."
          style={{ width: '100%' }}
          autoComplete="new-password"
        />
      </div>
      <div style={{ marginTop: '10px' }}>
        <button onClick={() => setSearchAsyncThrottler.flush()}>Flush</button>
      </div>
      {error && <div>Error: {error.message}</div>}
      <div>
        <p>API calls made: {setSearchAsyncThrottler.state.successCount}</p>
        {results.length > 0 && (
          <ul>
            {results.map((item) => (
              <li key={item.id}>{item.title}</li>
            ))}
          </ul>
        )}
        {setSearchAsyncThrottler.state.isPending ? (
          <p>Pending...</p>
        ) : setSearchAsyncThrottler.state.isExecuting ? (
          <p>Executing...</p>
        ) : null}
        <pre style={{ marginTop: '20px' }}>
          {JSON.stringify(setSearchAsyncThrottler.store.state, null, 2)}
        </pre>
      </div>
    </div>
  )
}

const root = ReactDOM.createRoot(document.getElementById('root')!)

// optionally, provide default options to an optional PacerProvider
root.render(
  <PacerProvider
  // defaultOptions={{
  //   throttler: {
  //     leading: true,
  //   },
  // }}
  >
    <App />
  </PacerProvider>,
)


import { useState } from 'react'
import ReactDOM from 'react-dom/client'
import { useAsyncThrottler } from '@tanstack/react-pacer/async-throttler'
import { PacerProvider } from '@tanstack/react-pacer/provider'

interface SearchResult {
  id: number
  title: string
}

// Simulate API call with fake data
const fakeApi = async (term: string): Promise<Array<SearchResult>> => {
  await new Promise((resolve) => setTimeout(resolve, 500)) // Simulate network delay
  return [\
    { id: 1, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
    { id: 2, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
    { id: 3, title: `${term} result ${Math.floor(Math.random() * 100)}` },\
  ]
}

function App() {
  const [searchTerm, setSearchTerm] = useState('')
  const [results, setResults] = useState<Array<SearchResult>>([])
  const [error, setError] = useState<Error | null>(null)

  // The function that will become throttled
  const handleSearch = async (term: string) => {
    if (!term) {
      setResults([])
      return
    }

    // throw new Error('Test error') // you don't have to catch errors here (though you still can). The onError optional handler will catch it

    const data = await fakeApi(term)
    setResults(data)
    setError(null)

    return data // this could alternatively be a void function without a return
  }

  // hook that gives you an async throttler instance
  const setSearchAsyncThrottler = useAsyncThrottler(
    handleSearch,
    {
      // leading: true, // default
      // trailing: true, // default
      wait: 1000, // Wait 1 second between API calls
      onError: (error) => {
        // optional error handler
        console.error('Search failed:', error)
        setError(error as Error)
        setResults([])
      },
      // throwOnError: true,
    },
    // Optional Selector function to pick the state you want to track and use
    (state) => state,
  )

  // get and name our throttled function
  const handleSearchThrottled = setSearchAsyncThrottler.maybeExecute

  // instant event handler that calls both the instant local state setter and the throttled function
  async function onSearchChange(e: React.ChangeEvent<HTMLInputElement>) {
    const newTerm = e.target.value
    setSearchTerm(newTerm)
    const result = await handleSearchThrottled(newTerm) // optionally await if you need to
    console.log('result', result)
  }

  return (
    <div>
      <h1>TanStack Pacer useAsyncThrottler Example</h1>
      <div>
        <input
          autoFocus
          type="search"
          value={searchTerm}
          onChange={onSearchChange}
          placeholder="Type to search..."
          style={{ width: '100%' }}
          autoComplete="new-password"
        />
      </div>
      <div style={{ marginTop: '10px' }}>
        <button onClick={() => setSearchAsyncThrottler.flush()}>Flush</button>
      </div>
      {error && <div>Error: {error.message}</div>}
      <div>
        <p>API calls made: {setSearchAsyncThrottler.state.successCount}</p>
        {results.length > 0 && (
          <ul>
            {results.map((item) => (
              <li key={item.id}>{item.title}</li>
            ))}
          </ul>
        )}
        {setSearchAsyncThrottler.state.isPending ? (
          <p>Pending...</p>
        ) : setSearchAsyncThrottler.state.isExecuting ? (
          <p>Executing...</p>
        ) : null}
        <pre style={{ marginTop: '20px' }}>
          {JSON.stringify(setSearchAsyncThrottler.store.state, null, 2)}
        </pre>
      </div>
    </div>
  )
}

const root = ReactDOM.createRoot(document.getElementById('root')!)

// optionally, provide default options to an optional PacerProvider
root.render(
  <PacerProvider
  // defaultOptions={{
  //   throttler: {
  //     leading: true,
  //   },
  // }}
  >
    <App />
  </PacerProvider>,
)

useThrottledValue

rateLimit

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