# useThrottledValue

# Function: useThrottledValue()

```ts
function useThrottledValue<TValue, TSelected>(
   value, 
   options, 
   selector?): [TValue, ReactThrottler<Dispatch<SetStateAction<TValue>>, TSelected>];
```

Defined in: [react-pacer/src/throttler/useThrottledValue.ts:82](https://github.com/TanStack/pacer/blob/main/packages/react-pacer/src/throttler/useThrottledValue.ts#L82)

A high-level React hook that creates a throttled version of a value that updates at most once within a specified time window.
This hook uses React's useState internally to manage the throttled state.

Throttling ensures the value updates occur at a controlled rate regardless of how frequently the input value changes.
This is useful for rate-limiting expensive re-renders or API calls that depend on rapidly changing values.

The hook returns a tuple containing:
- The throttled value that updates according to the leading/trailing edge behavior specified in the options
- The throttler instance with control methods

For more direct control over throttling behavior without React state management,
consider using the lower-level useThrottler hook instead.

## State Management and Selector

The hook uses TanStack Store for reactive state management via the underlying throttler instance.
The `selector` parameter allows you to specify which throttler 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 throttler state properties:
- `executionCount`: Number of function executions that have been completed
- `lastArgs`: The arguments from the most recent call to maybeExecute
- `lastExecutionTime`: Timestamp of the last function execution in milliseconds
- `nextExecutionTime`: Timestamp when the next execution can occur in milliseconds
- `isPending`: Whether the throttler is waiting for the timeout to trigger execution
- `status`: Current execution status ('disabled' | 'idle' | 'pending')

## Type Parameters

### TValue

`TValue`

### TSelected

`TSelected` = `ThrottlerState`\<`Dispatch`\<`SetStateAction`\<`TValue`\>\>\>

## Parameters

### value

`TValue`

### options

[`ReactThrottlerOptions`](../interfaces/ReactThrottlerOptions.md)\<`Dispatch`\<`SetStateAction`\<`TValue`\>\>, `TSelected`\>

### selector?

(`state`) => `TSelected`

## Returns

\[`TValue`, [`ReactThrottler`](../interfaces/ReactThrottler.md)\<`Dispatch`\<`SetStateAction`\<`TValue`\>\>, `TSelected`\>\]

## Example

```tsx
// Default behavior - no reactive state subscriptions
const [throttledValue, throttler] = useThrottledValue(rawValue, { wait: 1000 });

// Opt-in to re-render when execution count changes (optimized for tracking executions)
const [throttledValue, throttler] = useThrottledValue(
  rawValue,
  { wait: 1000 },
  (state) => ({ executionCount: state.executionCount })
);

// Opt-in to re-render when throttling state changes (optimized for loading indicators)
const [throttledValue, throttler] = useThrottledValue(
  rawValue,
  { wait: 1000 },
  (state) => ({
    isPending: state.isPending,
    status: state.status
  })
);

// Opt-in to re-render when timing information changes (optimized for timing displays)
const [throttledValue, throttler] = useThrottledValue(
  rawValue,
  { wait: 1000 },
  (state) => ({
    lastExecutionTime: state.lastExecutionTime,
    nextExecutionTime: state.nextExecutionTime
  })
);

// With custom leading/trailing behavior
const [throttledValue, throttler] = useThrottledValue(rawValue, {
  wait: 1000,
  leading: true,   // Update immediately on first change
  trailing: false  // Skip trailing edge updates
});

// Access the selected throttler state (will be empty object {} unless selector provided)
const { executionCount, isPending } = throttler.state;
```