Batching

Event batching allows you to group multiple events into a single network request under certain conditions. It is particularly useful in the following cases:

When using analytics services like Amplitude or Google Analytics that lack built-in batching
When you want to reduce the number of network requests
When you need to prevent event loss on browser close

Usage

Enable the batch option in the createTracker configuration to use batching.


const [Track, useTracker] = createTracker({
  // ... other configuration
  batch: {
    enable: true,
    interval: 2000,
    thresholdSize: 100,
    onFlush: (batch, isBrowserClosing) => {
      if (isBrowserClosing) {
        navigator.sendBeacon("/analytics/collect/batch", JSON.stringify(batch));
        return;
      }
 
      fetch("/analytics/collect/batch", {
        method: "POST",
        body: JSON.stringify(batch),
      });
    },
  },
});

Options

Option	Type	Description	Default
`enable`	`boolean`	Whether to enable batching	`false`
`interval`	`number`	Interval between batch sends (in ms)	`3000`
`thresholdSize`	`number`	Maximum number of events before flushing batch	`25`
`onFlush`	`(batch, isBrowserClosing) => void \| Promise<void>`	Required. Function to process batched events	-
`onError`	`(error: Error) => void \| Promise<void>`	Optional. Called when an error occurs during send	-

onFlush is required and defines how batched events are actually sent.

How It Works

The return value of each event handler is collected in memory.
onFlush is called when one of the following occurs:
- The interval time has elapsed
- The number of collected events reaches thresholdSize
- A browser close event is detected

Examples


const [Track, useTracker] = createTracker({
  DOMEvents: {
    onClick: (params, context) => {
      return {
        ...params,
        ...context,
        event_type: "click",
        timestamp: Date.now(),
      };
    },
  },
  batch: {
    enable: true,
    interval: 2000,
    thresholdSize: 100,
    onFlush: (batch, isBrowserClosing) => {
      if (isBrowserClosing) {
        navigator.sendBeacon("/analytics/collect/batch", JSON.stringify(batch));
        return;
      }
 
      fetch("/analytics/collect/batch", {
        method: "POST",
        body: JSON.stringify(batch),
      });
    },
  },
});
 
function App() {
  return (
    <Track.Provider initialContext={{ deviceId: "device-123" }}>
      <Track.Click params={{ buttonId: "submit" }}>
        <button>Submit</button>
      </Track.Click>
    </Track.Provider>
  );
}

Each time <Track.Click> runs, the object returned by the event handler is added to the batch queue.
After 2 seconds or once 100 events accumulate, onFlush is called and the batch is sent to the server.
On browser close, events are sent via sendBeacon.

Handling Browser Close

To prevent event loss when the browser closes, you can use navigator.sendBeacon:


onFlush: (batch, isBrowserClosing) => {
  if (isBrowserClosing) {
    navigator.sendBeacon("/analytics/collect/batch", JSON.stringify(batch));
    return;
  }
 
  fetch("/analytics/collect/batch", {
    method: "POST",
    body: JSON.stringify(batch),
  });
};

Notes

Only the return value of event handlers is batched. The handlers themselves are always executed.
Batched events are stored with context information.
Event order is preserved. For example, click → impression events are sent in the same order.
When the browser closes, the isBrowserClosing flag is set to true to allow conditional logic in onFlush.