updateHandler function

void updateHandler(
  1. Element element,
  2. String key,
  3. EventAttribute attr
)

Updates the handler wrapper for key on element with a new attr.

Called by _patchAttributes in diff.dart whenever a DOM node is reused at the same position. The JS listener stays registered — only the Dart callback it delegates to is updated.

Implementation

void updateHandler(Element element, String key, EventAttribute attr) {
  final map = _handlers[element];
  if (map != null && map.containsKey(key)) {
    map[key]!.attr = attr;
  } else {
    // Not yet registered — first time this event appears on this node.
    _registerHandler(element, key, attr);
  }
}