Make optional jQuery require bundler-friendly (#4184)

backbone.js

@@ -23,7 +23,13 @@
   // Next for Node.js or CommonJS. jQuery may not be needed as a module.
   } else if (typeof exports !== 'undefined') {
     var _ = require('underscore'), $;
-    try { $ = require('jquery'); } catch (e) {}
+    // Indirect the optional jQuery require through a variable so that
+    // Webpack, Rollup, esbuild, packd and friends do not try to resolve
+    // it at bundle time. The literal `require('jquery')` form was being
+    // statically analyzed by bundlers and failing the build for users
+    // who don't actually want jQuery (#4184).
+    var nodeRequire = typeof require === 'function' && require;
+    try { if (nodeRequire) $ = nodeRequire('jquery'); } catch (e) {}
     factory(root, exports, _, $);
 
   // Finally, as a browser global.

package.json

@@ -15,6 +15,14 @@
   "dependencies": {
     "underscore": ">=1.8.3"
   },
+  "peerDependencies": {
+    "jquery": ">=1.11.0"
+  },
+  "peerDependenciesMeta": {
+    "jquery": {
+      "optional": true
+    }
+  },
   "devDependencies": {
     "coffeescript": "^2.7.0",
     "cpy-cli": "^5.0.0",