From 472880a4c0722633b15d82359ffd4ecfec027827 Mon Sep 17 00:00:00 2001
From: Sophie Yang <syangabq@gmail.com>
Date: Mon, 22 Jan 2024 13:32:00 -0800
Subject: [PATCH] Use a more accurate heuristic for identifying ES6 classes
 (#49)

---
 src/manager.ts | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/manager.ts b/src/manager.ts
index b6d5ddd..6b04769 100644
--- a/src/manager.ts
+++ b/src/manager.ts
@@ -92,7 +92,7 @@ export class Manager extends ManagerBase implements IWidgetManager {
         // The ES6 classes cannot be subclassed via Backbone's extend that some
         // code uses, so if the export looks like a class use swizzle to make it
         // extensible.
-        if (value.prototype) {
+        if (isES6Class(value)) {
           value = swizzle(value);
         }
         module[key] = value;
@@ -107,7 +107,7 @@ export class Manager extends ManagerBase implements IWidgetManager {
         // The ES6 classes cannot be subclassed via Backbone's extend that some
         // code uses, so if the export looks like a class use swizzle to make it
         // extensible.
-        if (value.prototype) {
+        if (isES6Class(value)) {
           value = swizzle(value);
         }
         module[key] = value;
@@ -248,6 +248,10 @@ export class Manager extends ManagerBase implements IWidgetManager {
   }
 }
 
+function isES6Class(value: unknown): boolean {
+  return typeof value === 'function' && value.toString().startsWith('class ');
+}
+
 class ClassicComm implements IClassicComm {
   constructor(private readonly id: string, private readonly comm: IComm) {}
   get target_name() {