From e1d974be03c3b440f850d86923bbc250fa21189d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=A5kon=20L=C3=B8vdal?= <kode@denkule.no>
Date: Sun, 17 Sep 2023 17:31:42 +0200
Subject: [PATCH] Support loading ESM via dynamic import rather than require

---
 .../@node-red/registry/lib/loader.js          | 30 +++++++++++++++++--
 .../@node-red/registry/lib/loader_spec.js     |  2 +-
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/packages/node_modules/@node-red/registry/lib/loader.js b/packages/node_modules/@node-red/registry/lib/loader.js
index f3762ef36..678e4c885 100644
--- a/packages/node_modules/@node-red/registry/lib/loader.js
+++ b/packages/node_modules/@node-red/registry/lib/loader.js
@@ -344,9 +344,19 @@ function loadNodeSet(node) {
     } else {
     }
     try {
-        var r = require(node.file);
-        r = r.__esModule ? r.default : r;
-        return createLoadPromise(node, r);
+        let importPromise = import(node.file);
+        return importPromise
+            .then(function(module_namespace_object) {
+                // CJS will always have default, ESM might have default. (details in note below)
+                let r = module_namespace_object.default ? module_namespace_object.default : module_namespace_object;
+                // Babel related workaround. (references in note below)
+                r = r.__esModule ? r.default : r;
+                return createLoadPromise(node, r);
+            })
+            .catch(function(err) {
+                node.err = err;
+                return Promise.resolve(node);
+            });
     } catch(err) {
         node.err = err;
         var stack = err.stack;
@@ -371,6 +381,20 @@ function loadNodeSet(node) {
         return Promise.resolve(node);
     }
 
+    // Notes on default:
+    // https://nodejs.org/api/esm.html#import-expressions
+    // "When importing CommonJS modules, the module.exports object is provided as the default export."
+    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import
+    // "The module namespace object is a sealed object ... with the default export available as a key called `default`."
+
+    // Notes on __esModule:
+    // Workaround originally added in commit 326f3469, merged in pull request #3669.
+    // Related links:
+    // https://github.com/nodejs/node/issues/40891
+    // https://github.com/evanw/esbuild/issues/1591
+    // https://babeljs.io/docs/babel-plugin-transform-modules-commonjs
+    // https://stackoverflow.com/questions/50943704/whats-the-purpose-of-object-definepropertyexports-esmodule-value-0
+
     function createLoadPromise(node, r) {
         var loadPromise = null;
         if (typeof r === "function") {
diff --git a/test/unit/@node-red/registry/lib/loader_spec.js b/test/unit/@node-red/registry/lib/loader_spec.js
index b9da833c8..aec957b56 100644
--- a/test/unit/@node-red/registry/lib/loader_spec.js
+++ b/test/unit/@node-red/registry/lib/loader_spec.js
@@ -626,7 +626,7 @@ describe("red/nodes/registry/loader",function() {
                 node.enabled.should.be.true();
                 nodes.registerType.called.should.be.false();
                 node.should.have.property('err');
-                node.err.toString().should.eql("Error: fail to require (line:1)");
+                node.err.toString().should.eql("Error: fail to require");
 
                 done();
             }).catch(function(err) {