lib: implement queueMicrotask

PR-URL: https://github.com/nodejs/node/pull/22951
Refs: https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#dom-queuemicrotask
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

2 files changed, 60 insertions, 0 deletions

diff --git a/lib/internal/bootstrap/node.js b/lib/internal/bootstrap/node.js
index 8537131e8b..e1c56e9b7e 100644
--- a/lib/internal/bootstrap/node.js
+++ b/lib/internal/bootstrap/node.js
@@ -134,6 +134,7 @@
       setupGlobalConsole();
       setupGlobalURL();
       setupGlobalEncoding();
+      setupQueueMicrotask();
     }
 
     if (process.binding('config').experimentalWorker) {
@@ -527,6 +528,33 @@
     });
   }
 
+  function setupQueueMicrotask() {
+    const { queueMicrotask } = NativeModule.require('internal/queue_microtask');
+    Object.defineProperty(global, 'queueMicrotask', {
+      get: () => {
+        process.emitWarning('queueMicrotask() is experimental.',
+                            'ExperimentalWarning');
+        Object.defineProperty(global, 'queueMicrotask', {
+          value: queueMicrotask,
+          writable: true,
+          enumerable: false,
+          configurable: true,
+        });
+        return queueMicrotask;
+      },
+      set: (v) => {
+        Object.defineProperty(global, 'queueMicrotask', {
+          value: v,
+          writable: true,
+          enumerable: false,
+          configurable: true,
+        });
+      },
+      enumerable: false,
+      configurable: true,
+    });
+  }
+
   function setupDOMException() {
     // Registers the constructor with C++.
     NativeModule.require('internal/domexception');
diff --git a/lib/internal/queue_microtask.js b/lib/internal/queue_microtask.js
new file mode 100644
index 0000000000..3ff7ae9ae4
--- /dev/null
+++ b/lib/internal/queue_microtask.js
@@ -0,0 +1,32 @@
+'use strict';
+
+const { ERR_INVALID_ARG_TYPE } = require('internal/errors').codes;
+const { AsyncResource } = require('async_hooks');
+const { getDefaultTriggerAsyncId } = require('internal/async_hooks');
+const { internalBinding } = require('internal/bootstrap/loaders');
+const { enqueueMicrotask } = internalBinding('util');
+
+// declared separately for name, arrow function to prevent construction
+const queueMicrotask = (callback) => {
+  if (typeof callback !== 'function') {
+    throw new ERR_INVALID_ARG_TYPE('callback', 'function', callback);
+  }
+
+  const asyncResource = new AsyncResource('Microtask', {
+    triggerAsyncId: getDefaultTriggerAsyncId(),
+    requireManualDestroy: true,
+  });
+
+  enqueueMicrotask(() => {
+    asyncResource.runInAsyncScope(() => {
+      try {
+        callback();
+      } catch (e) {
+        process.emit('error', e);
+      }
+    });
+    asyncResource.emitDestroy();
+  });
+};
+
+module.exports = { queueMicrotask };