📄 tanstack/pacer/latest/docs/framework/react/examples/useQueuedState
File: useQueuedState.md | Updated: 11/15/2025
Source: https://tanstack.com/pacer/latest/docs/framework/react/examples/useQueuedState
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React Example: UseQueuedState
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tsx
import ReactDOM from 'react-dom/client'
import { useQueuedState } from '@tanstack/react-pacer/queuer'
import { useState } from 'react'
function App1() {
// Queuer that uses React.useState under the hood
function processItem(item: number) {
console.log('processing item', item)
}
const [queueItems, addItem, queuer] = useQueuedState(
processItem,
{
maxSize: 25,
initialItems: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
started: false,
wait: 1000, // wait 1 second between processing items - wait is optional!
},
// Optional Selector function to pick the state you want to track and use
(state) => ({
items: state.items, // required for useQueuedState
size: state.size,
isFull: state.isFull,
isEmpty: state.isEmpty,
isIdle: state.isIdle,
status: state.status,
executionCount: state.executionCount,
isRunning: state.isRunning,
}),
)
return (
<div>
<h1>TanStack Pacer useQueuedState Example 1</h1>
<div>Queue Size: {queuer.state.size}</div>
<div>Queue Max Size: {25}</div>
<div>Queue Full: {queuer.state.isFull ? 'Yes' : 'No'}</div>
<div>Queue Peek: {queuer.peekNextItem()}</div>
<div>Queue Empty: {queuer.state.isEmpty ? 'Yes' : 'No'}</div>
<div>Queue Idle: {queuer.state.isIdle ? 'Yes' : 'No'}</div>
<div>Queuer Status: {queuer.state.status}</div>
<div>Items Processed: {queuer.state.executionCount}</div>
<div>Queue Items: {queueItems.join(', ')}</div>
<div
style={{
display: 'grid',
gridTemplateColumns: 'repeat(2, 1fr)',
gap: '8px',
maxWidth: '600px',
margin: '16px 0',
}}
>
<button
onClick={() => {
const nextNumber = queueItems.length
? queueItems[queueItems.length - 1] + 1
: 1
addItem(nextNumber)
}}
disabled={queuer.state.isFull}
>
Add Number
</button>
<button
disabled={queuer.state.isEmpty}
onClick={() => {
queuer.execute()
}}
>
Process Next
</button>
<button onClick={() => queuer.clear()} disabled={queuer.state.isEmpty}>
Clear Queue
</button>
<button onClick={() => queuer.reset()} disabled={queuer.state.isEmpty}>
Reset Queue
</button>
<button
onClick={() => queuer.start()}
disabled={queuer.state.isRunning}
>
Start Processing
</button>
<button
onClick={() => queuer.stop()}
disabled={!queuer.state.isRunning}
>
Stop Processing
</button>
</div>
<pre style={{ marginTop: '20px' }}>
{JSON.stringify(queuer.store.state, null, 2)}
</pre>
</div>
)
}
function App2() {
const [currentValue, setCurrentValue] = useState(50)
const [queuedValue, setQueuedValue] = useState(50)
const [instantExecutionCount, setInstantExecutionCount] = useState(0)
// Queuer that processes a single value with delays
const [, addItem, queuer] = useQueuedState(
(item: number) => {
setQueuedValue(item)
},
{
maxSize: 100,
started: true,
wait: 100,
},
(state) => ({
items: state.items, // required for useQueuedState
size: state.size,
isFull: state.isFull,
isEmpty: state.isEmpty,
isIdle: state.isIdle,
status: state.status,
executionCount: state.executionCount,
isRunning: state.isRunning,
}),
)
function handleRangeChange(e: React.ChangeEvent<HTMLInputElement>) {
const newValue = parseInt(e.target.value, 10)
setCurrentValue(newValue)
setInstantExecutionCount((c) => c + 1)
addItem(newValue)
}
return (
<div>
<h1>TanStack Pacer useQueuedState Example 2</h1>
<div style={{ marginBottom: '20px' }}>
<label>
Current Range:
<input
type="range"
min="0"
max="100"
value={currentValue}
onChange={handleRangeChange}
style={{ width: '100%' }}
/>
<span>{currentValue}</span>
</label>
</div>
<div style={{ marginBottom: '20px' }}>
<label>
Queued Range (Readonly):
<input
type="range"
min="0"
max="100"
value={queuedValue}
readOnly
style={{ width: '100%' }}
/>
<span>{queuedValue}</span>
</label>
</div>
<table>
<tbody>
<tr>
<td>Queue Size:</td>
<td>{queuer.state.size}</td>
</tr>
<tr>
<td>Queue Full:</td>
<td>{queuer.state.isFull ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queue Empty:</td>
<td>{queuer.state.isEmpty ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queue Idle:</td>
<td>{queuer.state.isIdle ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queuer Status:</td>
<td>{queuer.state.status}</td>
</tr>
<tr>
<td>Instant Executions:</td>
<td>{instantExecutionCount}</td>
</tr>
<tr>
<td>Items Processed:</td>
<td>{queuer.state.executionCount}</td>
</tr>
<tr>
<td>Saved Executions:</td>
<td>{instantExecutionCount - queuer.state.executionCount}</td>
</tr>
<tr>
<td>% Reduction:</td>
<td>
{instantExecutionCount === 0
? '0'
: Math.round(
((instantExecutionCount - queuer.state.executionCount) /
instantExecutionCount) *
100,
)}
%
</td>
</tr>
</tbody>
</table>
<div style={{ color: '#666', fontSize: '0.9em' }}>
<p>Queued with 100ms wait time</p>
</div>
<pre style={{ marginTop: '20px' }}>
{JSON.stringify(queuer.store.state, null, 2)}
</pre>
</div>
)
}
const root = ReactDOM.createRoot(document.getElementById('root')!)
root.render(
<div>
<App1 />
<hr />
<App2 />
</div>,
)
import ReactDOM from 'react-dom/client'
import { useQueuedState } from '@tanstack/react-pacer/queuer'
import { useState } from 'react'
function App1() {
// Queuer that uses React.useState under the hood
function processItem(item: number) {
console.log('processing item', item)
}
const [queueItems, addItem, queuer] = useQueuedState(
processItem,
{
maxSize: 25,
initialItems: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
started: false,
wait: 1000, // wait 1 second between processing items - wait is optional!
},
// Optional Selector function to pick the state you want to track and use
(state) => ({
items: state.items, // required for useQueuedState
size: state.size,
isFull: state.isFull,
isEmpty: state.isEmpty,
isIdle: state.isIdle,
status: state.status,
executionCount: state.executionCount,
isRunning: state.isRunning,
}),
)
return (
<div>
<h1>TanStack Pacer useQueuedState Example 1</h1>
<div>Queue Size: {queuer.state.size}</div>
<div>Queue Max Size: {25}</div>
<div>Queue Full: {queuer.state.isFull ? 'Yes' : 'No'}</div>
<div>Queue Peek: {queuer.peekNextItem()}</div>
<div>Queue Empty: {queuer.state.isEmpty ? 'Yes' : 'No'}</div>
<div>Queue Idle: {queuer.state.isIdle ? 'Yes' : 'No'}</div>
<div>Queuer Status: {queuer.state.status}</div>
<div>Items Processed: {queuer.state.executionCount}</div>
<div>Queue Items: {queueItems.join(', ')}</div>
<div
style={{
display: 'grid',
gridTemplateColumns: 'repeat(2, 1fr)',
gap: '8px',
maxWidth: '600px',
margin: '16px 0',
}}
>
<button
onClick={() => {
const nextNumber = queueItems.length
? queueItems[queueItems.length - 1] + 1
: 1
addItem(nextNumber)
}}
disabled={queuer.state.isFull}
>
Add Number
</button>
<button
disabled={queuer.state.isEmpty}
onClick={() => {
queuer.execute()
}}
>
Process Next
</button>
<button onClick={() => queuer.clear()} disabled={queuer.state.isEmpty}>
Clear Queue
</button>
<button onClick={() => queuer.reset()} disabled={queuer.state.isEmpty}>
Reset Queue
</button>
<button
onClick={() => queuer.start()}
disabled={queuer.state.isRunning}
>
Start Processing
</button>
<button
onClick={() => queuer.stop()}
disabled={!queuer.state.isRunning}
>
Stop Processing
</button>
</div>
<pre style={{ marginTop: '20px' }}>
{JSON.stringify(queuer.store.state, null, 2)}
</pre>
</div>
)
}
function App2() {
const [currentValue, setCurrentValue] = useState(50)
const [queuedValue, setQueuedValue] = useState(50)
const [instantExecutionCount, setInstantExecutionCount] = useState(0)
// Queuer that processes a single value with delays
const [, addItem, queuer] = useQueuedState(
(item: number) => {
setQueuedValue(item)
},
{
maxSize: 100,
started: true,
wait: 100,
},
(state) => ({
items: state.items, // required for useQueuedState
size: state.size,
isFull: state.isFull,
isEmpty: state.isEmpty,
isIdle: state.isIdle,
status: state.status,
executionCount: state.executionCount,
isRunning: state.isRunning,
}),
)
function handleRangeChange(e: React.ChangeEvent<HTMLInputElement>) {
const newValue = parseInt(e.target.value, 10)
setCurrentValue(newValue)
setInstantExecutionCount((c) => c + 1)
addItem(newValue)
}
return (
<div>
<h1>TanStack Pacer useQueuedState Example 2</h1>
<div style={{ marginBottom: '20px' }}>
<label>
Current Range:
<input
type="range"
min="0"
max="100"
value={currentValue}
onChange={handleRangeChange}
style={{ width: '100%' }}
/>
<span>{currentValue}</span>
</label>
</div>
<div style={{ marginBottom: '20px' }}>
<label>
Queued Range (Readonly):
<input
type="range"
min="0"
max="100"
value={queuedValue}
readOnly
style={{ width: '100%' }}
/>
<span>{queuedValue}</span>
</label>
</div>
<table>
<tbody>
<tr>
<td>Queue Size:</td>
<td>{queuer.state.size}</td>
</tr>
<tr>
<td>Queue Full:</td>
<td>{queuer.state.isFull ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queue Empty:</td>
<td>{queuer.state.isEmpty ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queue Idle:</td>
<td>{queuer.state.isIdle ? 'Yes' : 'No'}</td>
</tr>
<tr>
<td>Queuer Status:</td>
<td>{queuer.state.status}</td>
</tr>
<tr>
<td>Instant Executions:</td>
<td>{instantExecutionCount}</td>
</tr>
<tr>
<td>Items Processed:</td>
<td>{queuer.state.executionCount}</td>
</tr>
<tr>
<td>Saved Executions:</td>
<td>{instantExecutionCount - queuer.state.executionCount}</td>
</tr>
<tr>
<td>% Reduction:</td>
<td>
{instantExecutionCount === 0
? '0'
: Math.round(
((instantExecutionCount - queuer.state.executionCount) /
instantExecutionCount) *
100,
)}
%
</td>
</tr>
</tbody>
</table>
<div style={{ color: '#666', fontSize: '0.9em' }}>
<p>Queued with 100ms wait time</p>
</div>
<pre style={{ marginTop: '20px' }}>
{JSON.stringify(queuer.store.state, null, 2)}
</pre>
</div>
)
}
const root = ReactDOM.createRoot(document.getElementById('root')!)
root.render(
<div>
<App1 />
<hr />
<App2 />
</div>,
)
