revamp batching implementation to batch in longer sequences

Author: theKashey

src/utils/batched-updates.js

@@ -1,31 +1,43 @@
 /* eslint-disable import/no-unresolved */
-import { unstable_batchedUpdates } from 'react-dom';
+import {unstable_batchedUpdates} from 'react-dom';
 import {
-  unstable_scheduleCallback as scheduleCallback,
-  unstable_ImmediatePriority as ImmediatePriority,
+    unstable_scheduleCallback as scheduleCallback,
+    unstable_ImmediatePriority as ImmediatePriority,
 } from 'scheduler';
 
 import defaults from '../defaults';
 import supports from './supported-features';
 
-let isInsideBatchedSchedule = 0;
+let batchedScheduled = false;
+
+let batched = [];
+
+const executeBatched = () => {
+    unstable_batchedUpdates(() => {
+        while (batched.length) {
+            const currentBatched = batched;
+            batched = [];
+            currentBatched.forEach(fn => fn());
+        }
+        // important to reset it before exiting this function
+        // as React will dump everything right after
+        batchedScheduled = false;
+    });
+}
 
 export function batch(fn) {
-  // if we are in node/tests or nested schedule
-  if (
-    !defaults.batchUpdates ||
-    !supports.scheduling() ||
-    isInsideBatchedSchedule
-  ) {
-    return unstable_batchedUpdates(fn);
-  }
+    // if we are in node/tests or nested schedule
+    if (
+        !defaults.batchUpdates ||
+        !supports.scheduling()
+    ) {
+        return unstable_batchedUpdates(fn);
+    }
+
+    batched.push(fn);
 
-  isInsideBatchedSchedule = 0;
-  // Use ImmediatePriority as it has -1ms timeout
-  // https://github.com/facebook/react/blob/main/packages/scheduler/src/forks/Scheduler.js#L65
-  return scheduleCallback(ImmediatePriority, function scheduleBatchedUpdates() {
-    isInsideBatchedSchedule++;
-    unstable_batchedUpdates(fn);
-    isInsideBatchedSchedule--;
-  });
+    if (!batchedScheduled) {
+        batchedScheduled = true;
+        return scheduleCallback(ImmediatePriority, executeBatched);
+    }
 }