extractCompositionEvent() — react Function Reference

Source Code

packages/react-dom-bindings/src/events/plugins/BeforeInputEventPlugin.js lines 194–253

function extractCompositionEvent(
  dispatchQueue: DispatchQueue,
  domEventName: DOMEventName,
  targetInst: null | Fiber,
  nativeEvent: AnyNativeEvent,
  nativeEventTarget: null | EventTarget,
) {
  let eventType;
  let fallbackData;

  if (canUseCompositionEvent) {
    eventType = getCompositionEventType(domEventName);
  } else if (!isComposing) {
    if (isFallbackCompositionStart(domEventName, nativeEvent)) {
      eventType = 'onCompositionStart';
    }
  } else if (isFallbackCompositionEnd(domEventName, nativeEvent)) {
    eventType = 'onCompositionEnd';
  }

  if (!eventType) {
    return null;
  }

  if (useFallbackCompositionData && !isUsingKoreanIME(nativeEvent)) {
    // The current composition is stored statically and must not be
    // overwritten while composition continues.
    if (!isComposing && eventType === 'onCompositionStart') {
      isComposing = FallbackCompositionStateInitialize(nativeEventTarget);
    } else if (eventType === 'onCompositionEnd') {
      if (isComposing) {
        fallbackData = FallbackCompositionStateGetData();
      }
    }
  }

  const listeners = accumulateTwoPhaseListeners(targetInst, eventType);
  if (listeners.length > 0) {
    const event: ReactSyntheticEvent = new SyntheticCompositionEvent(
      eventType,
      domEventName,
      null,
      nativeEvent,
      nativeEventTarget,
    );
    dispatchQueue.push({event, listeners});
    if (fallbackData) {
      // Inject data generated from fallback path into the synthetic event.
      // This matches the property of native CompositionEventInterface.
      // $FlowFixMe[incompatible-use]
      event.data = fallbackData;
    } else {
      const customData = getDataFromCustomEvent(nativeEvent);
      if (customData !== null) {
        // $FlowFixMe[incompatible-use]
        event.data = customData;
      }
    }
  }
}