Add methodNotAllowedCatcher Middleware and Example

lib/express.js

@@ -6,19 +6,19 @@
  * MIT Licensed
  */
 
-'use strict';
+"use strict";
 
 /**
  * Module dependencies.
  */
 
-var bodyParser = require('body-parser')
-var EventEmitter = require('node:events').EventEmitter;
-var mixin = require('merge-descriptors');
-var proto = require('./application');
-var Router = require('router');
-var req = require('./request');
-var res = require('./response');
+var bodyParser = require("body-parser");
+var EventEmitter = require("node:events").EventEmitter;
+var mixin = require("merge-descriptors");
+var proto = require("./application");
+var Router = require("router");
+var req = require("./request");
+var res = require("./response");
 
 /**
  * Expose `createApplication()`.
@@ -33,8 +33,13 @@ exports = module.exports = createApplication;
  * @api public
  */
 
+/**
+ * Expose methodNotAllowedCatcher middleware
+ */
+exports.methodNotAllowedCatcher = require("./methodNotAllowedCatcher");
+
 function createApplication() {
-  var app = function(req, res, next) {
+  var app = function (req, res, next) {
     app.handle(req, res, next);
   };
 
@@ -43,13 +48,13 @@ function createApplication() {
 
   // expose the prototype that will get set on requests
   app.request = Object.create(req, {
-    app: { configurable: true, enumerable: true, writable: true, value: app }
-  })
+    app: { configurable: true, enumerable: true, writable: true, value: app },
+  });
 
   // expose the prototype that will get set on responses
   app.response = Object.create(res, {
-    app: { configurable: true, enumerable: true, writable: true, value: app }
-  })
+    app: { configurable: true, enumerable: true, writable: true, value: app },
+  });
 
   app.init();
   return app;
@@ -74,8 +79,8 @@ exports.Router = Router;
  * Expose middleware
  */
 
-exports.json = bodyParser.json
-exports.raw = bodyParser.raw
-exports.static = require('serve-static');
-exports.text = bodyParser.text
-exports.urlencoded = bodyParser.urlencoded
+exports.json = bodyParser.json;
+exports.raw = bodyParser.raw;
+exports.static = require("serve-static");
+exports.text = bodyParser.text;
+exports.urlencoded = bodyParser.urlencoded;

lib/methodNotAllowedCatcher.js

@@ -0,0 +1,15 @@
+// Helper middleware to send 405 Method Not Allowed and set Allow header
+function methodNotAllowedCatcher(req, res) {
+  if (req.route && req.route.stack) {
+    // Collect allowed methods from the route stack
+    const allowed = req.route.stack
+      .map((layer) => layer.method && layer.method.toUpperCase())
+      .filter(Boolean);
+    if (allowed.length > 0) {
+      res.set("Allow", allowed.join(", "));
+    }
+  }
+  res.sendStatus(405);
+}
+
+module.exports = methodNotAllowedCatcher;