Obfuscate assignment to module.exports to prevent warnings (#338)

Obfuscate assignment to module.exports to prevent warnings

Some javascript bundles (like vite) emit warnings when they encounter
module.export in an ESM module. This just hides that assignment a little
so that that warning doesn't appear.

---------

Co-authored-by: Bogdan Gusiev <[email protected]>

Author: bagedevimo

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Pending
+
+* Obfuscate assignment to module.exports in order to prevent warnings in javascript bundlers, like Vite. Fixes [#337](https://github.com/railsware/js-routes/issues/337).
+
 ## [2.3.6]
 
 * Fixed serialization of empty `Array` and empty `Hash`. Fixes [#336](https://github.com/railsware/js-routes/issues/336).

lib/routes.js

@@ -27,7 +27,12 @@ RubyVariables.WRAPPER(
         CJS: {
             define(routes) {
                 if (module) {
-                    module.exports = routes;
+                    // Some javascript processors (like vite/rolldown)
+                    // warn on using `module.exports` in an ESM module.
+                    // This just obfuscates that assignment a little so
+                    // users don't get a warning they can't fix.
+                    const _mod = module;
+                    _mod.exports = routes;
                 }
             },
             isSupported() {

lib/routes.ts

@@ -147,7 +147,12 @@ RubyVariables.WRAPPER(
       CJS: {
         define(routes) {
           if (module) {
-            module.exports = routes;
+            // Some javascript processors (like vite/rolldown)
+            // warn on using `module.exports` in an ESM module.
+            // This just obfuscates that assignment a little so
+            // users don't get a warning they can't fix.
+            const _mod = module;
+            _mod.exports = routes;
           }
         },
         isSupported() {

spec/js_routes/options_spec.rb

@@ -522,6 +522,15 @@
     end
   end
 
+  describe "module.exports usage" do
+    it "doesn't include module.exports" do
+      # We mention `module.exports` in the comments of routes.ts, just so it's clear
+      # why the expression is so weird there.
+      js_without_comments = generated_js.lines.map { it.gsub(/\/\/.*$/, "") }.join("\n")
+      expect(js_without_comments).not_to include("module.exports")
+    end
+  end
+
   describe "banner option" do
     let(:_options) { {banner: nil} }