8 files changed, 91 insertions, 4 deletions
diff --git a/cli/tests/integration/run_tests.rs b/cli/tests/integration/run_tests.rs
index 9c60cc745..8998eecc9 100644
--- a/cli/tests/integration/run_tests.rs
+++ b/cli/tests/integration/run_tests.rs
@@ -2745,6 +2745,17 @@ itest!(report_error_end_of_program {
   exit_code: 1,
 });
 
+itest!(queue_microtask_error {
+  args: "run --quiet queue_microtask_error.ts",
+  output: "queue_microtask_error.ts.out",
+  exit_code: 1,
+});
+
+itest!(queue_microtask_error_handled {
+  args: "run --quiet queue_microtask_error_handled.ts",
+  output: "queue_microtask_error_handled.ts.out",
+});
+
 itest!(spawn_stdout_inherit {
   args: "run --quiet --unstable -A spawn_stdout_inherit.ts",
   output: "spawn_stdout_inherit.ts.out",
diff --git a/cli/tests/testdata/queue_microtask_error.ts b/cli/tests/testdata/queue_microtask_error.ts
new file mode 100644
index 000000000..b2e9642c5
--- /dev/null
+++ b/cli/tests/testdata/queue_microtask_error.ts
@@ -0,0 +1,5 @@
+queueMicrotask(() => {
+  throw new Error("foo");
+});
+console.log(1);
+Promise.resolve().then(() => console.log(2));
diff --git a/cli/tests/testdata/queue_microtask_error.ts.out b/cli/tests/testdata/queue_microtask_error.ts.out
new file mode 100644
index 000000000..6c4d41936
--- /dev/null
+++ b/cli/tests/testdata/queue_microtask_error.ts.out
@@ -0,0 +1,6 @@
+1
+error: Uncaught Error: foo
+  throw new Error("foo");
+        ^
+    at [WILDCARD]/queue_microtask_error.ts:2:9
+    at deno:core/[WILDCARD]
diff --git a/cli/tests/testdata/queue_microtask_error_handled.ts b/cli/tests/testdata/queue_microtask_error_handled.ts
new file mode 100644
index 000000000..7d1440135
--- /dev/null
+++ b/cli/tests/testdata/queue_microtask_error_handled.ts
@@ -0,0 +1,21 @@
+addEventListener("error", (event) => {
+  console.log({
+    cancelable: event.cancelable,
+    message: event.message,
+    filename: event.filename,
+    lineno: event.lineno,
+    colno: event.colno,
+    error: event.error,
+  });
+  event.preventDefault();
+});
+
+onerror = (event) => {
+  console.log("onerror() called", event.error);
+};
+
+queueMicrotask(() => {
+  throw new Error("foo");
+});
+console.log(1);
+Promise.resolve().then(() => console.log(2));
diff --git a/cli/tests/testdata/queue_microtask_error_handled.ts.out b/cli/tests/testdata/queue_microtask_error_handled.ts.out
new file mode 100644
index 000000000..7f3f7f84a
--- /dev/null
+++ b/cli/tests/testdata/queue_microtask_error_handled.ts.out
@@ -0,0 +1,15 @@
+1
+{
+  cancelable: true,
+  message: "Uncaught Error: foo",
+  filename: "[WILDCARD]/queue_microtask_error_handled.ts",
+  lineno: 18,
+  colno: 9,
+  error: Error: foo
+    at [WILDCARD]/queue_microtask_error_handled.ts:18:9
+    at deno:core/[WILDCARD]
+}
+onerror() called Error: foo
+    at [WILDCARD]/queue_microtask_error_handled.ts:18:9
+    at deno:core/[WILDCARD]
+2
diff --git a/core/01_core.js b/core/01_core.js
index aaff59148..e1ac275eb 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -210,8 +210,35 @@
     return aggregate;
   }
 
+  let reportExceptionCallback = undefined;
+
+  // Used to report errors thrown from functions passed to `queueMicrotask()`.
+  // The callback will be passed the thrown error. For example, you can use this
+  // to dispatch an error event to the global scope.
+  // In other words, set the implementation for
+  // https://html.spec.whatwg.org/multipage/webappapis.html#report-the-exception
+  function setReportExceptionCallback(cb) {
+    if (typeof cb != "function") {
+      throw new TypeError("expected a function");
+    }
+    reportExceptionCallback = cb;
+  }
+
   function queueMicrotask(cb) {
-    return ops.op_queue_microtask(cb);
+    if (typeof cb != "function") {
+      throw new TypeError("expected a function");
+    }
+    return ops.op_queue_microtask(() => {
+      try {
+        cb();
+      } catch (error) {
+        if (reportExceptionCallback) {
+          reportExceptionCallback(error);
+        } else {
+          throw error;
+        }
+      }
+    });
   }
 
   // Some "extensions" rely on "BadResource" and "Interrupted" errors in the
@@ -252,6 +279,7 @@
     opCallTraces,
     refOp,
     unrefOp,
+    setReportExceptionCallback,
     close: (rid) => ops.op_close(rid),
     tryClose: (rid) => ops.op_try_close(rid),
     read: opAsync.bind(null, "op_read"),
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index cbc5c1b5b..b25022a08 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -76,7 +76,7 @@ delete Intl.v8BreakIterator;
   const errors = window.__bootstrap.errors.errors;
   const webidl = window.__bootstrap.webidl;
   const domException = window.__bootstrap.domException;
-  const { defineEventHandler } = window.__bootstrap.event;
+  const { defineEventHandler, reportException } = window.__bootstrap.event;
   const { deserializeJsMessageData, serializeJsMessageData } =
     window.__bootstrap.messagePort;
 
@@ -243,6 +243,7 @@ delete Intl.v8BreakIterator;
     core.setMacrotaskCallback(timers.handleTimerMacrotask);
     core.setMacrotaskCallback(promiseRejectMacrotaskCallback);
     core.setWasmStreamingCallback(fetch.handleWasmStreaming);
+    core.setReportExceptionCallback(reportException);
     ops.op_set_format_exception_callback(formatException);
     version.setVersions(
       runtimeOptions.denoVersion,
diff --git a/tools/wpt/expectation.json b/tools/wpt/expectation.json
index 813abbbba..39fe59515 100644
--- a/tools/wpt/expectation.json
+++ b/tools/wpt/expectation.json
@@ -3615,7 +3615,7 @@
         "type-long-settimeout.any.worker.html": true
       },
       "microtask-queuing": {
-        "queue-microtask-exceptions.any.html": false,
+        "queue-microtask-exceptions.any.html": true,
         "queue-microtask.any.html": true,
         "queue-microtask.any.worker.html": true
       },
@@ -4610,4 +4610,4 @@
     "idlharness.https.any.worker.html": true,
     "idlharness-shadowrealm.window.html": false
   }
-}
-\ No newline at end of file
+}