1 files changed, 30 insertions, 3 deletions
diff --git a/runtime/js/01_web_util.js b/runtime/js/01_web_util.js
index 4a9825fa1..9b51021f9 100644
--- a/runtime/js/01_web_util.js
+++ b/runtime/js/01_web_util.js
@@ -27,17 +27,41 @@
   }
 
   const handlerSymbol = Symbol("eventHandlers");
-  function makeWrappedHandler(handler) {
+  function makeWrappedHandler(handler, isSpecialErrorEventHandler) {
     function wrappedHandler(...args) {
       if (typeof wrappedHandler.handler !== "function") {
         return;
       }
+      if (isSpecialErrorEventHandler) {
+        const evt = args[0];
+        if (evt instanceof ErrorEvent && evt.type === "error") {
+          const ret = FunctionPrototypeCall(
+            wrappedHandler.handler,
+            this,
+            evt.message,
+            evt.filename,
+            evt.lineno,
+            evt.colno,
+            evt.error,
+          );
+          if (ret === true) {
+            evt.preventDefault();
+          }
+          return;
+        }
+      }
+
       return FunctionPrototypeCall(wrappedHandler.handler, this, ...args);
     }
     wrappedHandler.handler = handler;
     return wrappedHandler;
   }
-  function defineEventHandler(emitter, name, defaultValue = undefined) {
+  function defineEventHandler(
+    emitter,
+    name,
+    defaultValue = undefined,
+    isSpecialErrorEventHandler = false,
+  ) {
     // HTML specification section 8.1.5.1
     ObjectDefineProperty(emitter, `on${name}`, {
       get() {
@@ -56,7 +80,10 @@
         if (handlerWrapper) {
           handlerWrapper.handler = value;
         } else {
-          handlerWrapper = makeWrappedHandler(value);
+          handlerWrapper = makeWrappedHandler(
+            value,
+            isSpecialErrorEventHandler,
+          );
           this.addEventListener(name, handlerWrapper);
         }
         MapPrototypeSet(this[handlerSymbol], name, handlerWrapper);