put listener check in a utility

devdoshi · Aug 8, 2022 · d455680 · d455680
1 parent 37796ee
commit d455680
Showing 1 changed file with 13 additions and 9 deletions.
diff --git a/src/crank.ts b/src/crank.ts
@@ -1617,10 +1617,7 @@ export class Context<TProps = any, TResult = any> implements EventTarget {
  ): void {
  const impl = this[$ContextImpl];
  let listeners: Array<EventListenerRecord>;
- if (
- (typeof listener !== "function" && typeof listener !== "object") ||
- listener === null
- ) {
+ if (!isListenerOrListenerObject(listener)) {
  return;
  } else {
  const listeners1 = listenersMap.get(impl);
@@ -1680,11 +1677,7 @@ export class Context<TProps = any, TResult = any> implements EventTarget {
  ): void {
  const impl = this[$ContextImpl];
  const listeners = listenersMap.get(impl);
- if (
- listeners == null ||
- (typeof listener !== "function" && typeof listener !== "object") ||
- listener === null
- ) {
+ if (listeners == null || !isListenerOrListenerObject(listener)) {
  return;
  }
 
@@ -2329,6 +2322,17 @@ type MappedEventListenerOrEventListenerObject<T extends string> =
  | MappedEventListener<T>
  | {handleEvent: MappedEventListener<T>};
 
+function isListenerOrListenerObject(
+ value: unknown,
+): value is MappedEventListenerOrEventListenerObject<string> {
+ return (
+ typeof value === "function" ||
+ (value !== null &&
+ typeof value === "object" &&
+ typeof (value as any).handleEvent === "function")
+ );
+}
+
 interface EventListenerRecord {
  type: string;
  callback: MappedEventListener<any>;