Merge pull request #413 from arv/error-in-events

Rethrow erors in events

src/wrappers/events.js

@@ -165,12 +165,22 @@
     return getTreeScope(a) === getTreeScope(b);
   }
 
+  // pendingError is used to rethrow the first error we got during an event
+  // dispatch. The browser actually reports all errors but to do that we would
+  // need to rethrow the error asynchronously.
+  var pendingError;
+
   function dispatchOriginalEvent(originalEvent) {
     // Make sure this event is only dispatched once.
     if (handledEventsTable.get(originalEvent))
       return;
     handledEventsTable.set(originalEvent, true);
     dispatchEvent(wrap(originalEvent), wrap(originalEvent.target));
+    if (pendingError) {
+      var err = pendingError;
+      pendingError = null;
+      throw err;
+    }
   }
 
   function isLoadLikeEvent(event) {
@@ -324,10 +334,8 @@
           return false;
 
       } catch (ex) {
-        if (window.onerror)
-          window.onerror(ex.message);
-        else
-          console.error(ex, ex.stack);
+        if (!pendingError)
+          pendingError = ex;
       }
     }
 

test/js/events.js

@@ -1385,4 +1385,30 @@ test('retarget order (multiple shadow roots)', function() {
     assert.isFalse(checkbox.checked);
   });
 
+  test('window.onerror', function() {
+    var old = window.onerror;
+    var f;
+    var msg = 'Intentional error';
+    var errorCount = 0;
+
+    window.onerror = function(msg, source, lineNumber, columnNumber, error) {
+      document.removeEventListener('click', f);
+      window.onerror = old;
+      assert.isTrue(msg.indexOf(msg) >= 0);
+      assert.typeOf(source, 'string');
+      assert.typeOf(lineNumber, 'number');
+      assert.typeOf(columnNumber, 'number');
+      // error is not available in IE11.
+      errorCount++;
+    };
+
+    document.addEventListener('click', f = function(e) {
+      throw new Error(msg);
+    });
+
+    document.body.click();
+
+    assert.equal(errorCount, 1);
+  });
+
 });