events: simplify event target agnostic logic in on and once

PR-URL: #34997 Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
nodejs · Sep 11, 2020 · b1831fe · b1831fe
1 parent c66e647
commit b1831fe
Showing 1 changed file with 10 additions and 36 deletions.
diff --git a/lib/events.js b/lib/events.js
@@ -642,11 +642,7 @@ async function once(emitter, name, options = {}) {
     const errorListener = (err) => {
       emitter.removeListener(name, resolver);
       if (signal != null) {
-        eventTargetAgnosticRemoveListener(
-          signal,
-          'abort',
-          abortListener,
-          { once: true });
+        eventTargetAgnosticRemoveListener(signal, 'abort', abortListener);
       }
       reject(err);
     };
@@ -655,38 +651,22 @@ async function once(emitter, name, options = {}) {
         emitter.removeListener('error', errorListener);
       }
       if (signal != null) {
-        eventTargetAgnosticRemoveListener(
-          signal,
-          'abort',
-          abortListener,
-          { once: true });
+        eventTargetAgnosticRemoveListener(signal, 'abort', abortListener);
       }
       resolve(args);
     };
     eventTargetAgnosticAddListener(emitter, name, resolver, { once: true });
-    if (name !== 'error') {
-      addErrorHandlerIfEventEmitter(emitter, errorListener, { once: true });
+    if (name !== 'error' && typeof emitter.once === 'function') {
+      emitter.once('error', errorListener);
     }
     function abortListener() {
-      if (typeof emitter.removeListener === 'function') {
-        emitter.removeListener(name, resolver);
-        emitter.removeListener('error', errorListener);
-      } else {
-        eventTargetAgnosticRemoveListener(
-          emitter,
-          name,
-          resolver,
-          { once: true });
-        eventTargetAgnosticRemoveListener(
-          emitter,
-          'error',
-          errorListener,
-          { once: true });
-      }
+      eventTargetAgnosticRemoveListener(emitter, name, resolver);
+      eventTargetAgnosticRemoveListener(emitter, 'error', resolver);
       reject(lazyDOMException('The operation was aborted', 'AbortError'));
     }
     if (signal != null) {
-      signal.addEventListener('abort', abortListener, { once: true });
+      eventTargetAgnosticAddListener(
+        signal, 'abort', abortListener, { once: true });
     }
   });
 }
@@ -698,12 +678,6 @@ function createIterResult(value, done) {
   return { value, done };
 }
 
-function addErrorHandlerIfEventEmitter(emitter, handler, flags) {
-  if (typeof emitter.on === 'function') {
-    eventTargetAgnosticAddListener(emitter, 'error', handler, flags);
-  }
-}
-
 function eventTargetAgnosticRemoveListener(emitter, name, listener, flags) {
   if (typeof emitter.removeListener === 'function') {
     emitter.removeListener(name, listener);
@@ -808,8 +782,8 @@ function on(emitter, event, options) {
   }, AsyncIteratorPrototype);
 
   eventTargetAgnosticAddListener(emitter, event, eventHandler);
-  if (event !== 'error') {
-    addErrorHandlerIfEventEmitter(emitter, errorHandler);
+  if (event !== 'error' && typeof emitter.on === 'function') {
+    emitter.on('error', errorHandler);
   }
 
   if (signal) {