Generator support

.editorconfig

@@ -0,0 +1,13 @@
+# editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+indent_size = 2
+indent_style = space
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false

.eslintrc.js

@@ -0,0 +1,17 @@
+'use strict';
+
+/** @type {import('eslint').Linter.Config} */
+module.exports = {
+  extends: 'airbnb-base',
+  parserOptions: {
+    sourceType: 'script'
+  },
+  rules: {
+    strict: ['error', 'safe'],
+    'no-underscore-dangle': 'off',
+    'no-param-reassign': 'off',
+    'no-unused-vars': ['error', { 'argsIgnorePattern': 'next|res|req|err' }],
+    'func-names': ['error', 'always', { generators: 'never' }],
+    'require-yield': 'off'
+  }
+};

.gitignore

@@ -2,3 +2,4 @@ node_modules
 .nyc_output/
 .tern-port
 coverage/
+.DS_Store

.travis.yml

@@ -1,7 +1,15 @@
 language: node_js
 node_js:
-  - "node"
   - "8"
+  - "10"
+  - "12"
+  - lts/*
+  - node
+
+script:
+  - yarn lint
+  - yarn test
+
 deploy:
   provider: npm
   email: [email protected]

README.md

@@ -1,8 +1,10 @@
 # ExpressJS Async Errors
 
-[![Build Status](https://travis-ci.org/davidbanham/express-async-errors.svg?branch=master)](https://travis-ci.org/davidbanham/express-async-errors)
+[![build status](https://badgen.net/travis/davidbanham/express-async-errors/master)](https://travis-ci.com/davidbanham/express-async-errors)
+[![install size](https://badgen.net/packagephobia/install/express-async-errors)](https://packagephobia.now.sh/result?p=express-async-errors)
+[![npm package version](https://badgen.net/npm/v/express-async-errors)](https://npm.im/express-async-errors)
 
-A dead simple ES6 async/await support hack for [ExpressJS](http://expressjs.com)
+A dead simple ES6 generators and async/await support hack for [ExpressJS](http://expressjs.com)
 
 Shamelessly copied from [express-yields](https://github.com/MadRabbit/express-yields)
 
@@ -14,7 +16,7 @@ This has been lightly reworked to handle async rather than generators.
 npm install express-async-errors --save
 ```
 
-Then require this script somewhere __before__ you start using it:
+Then require this script somewhere **before** you start using it:
 
 Async functions already work fine in Express.
 
@@ -28,6 +30,12 @@ app.get('/users', async (req, res) => {
   const users = await User.findAll();
   res.send(users);
 });
+
+// or with generators
+app.get('/users', function* (req, res) {
+  const users = yield User.findAll();
+  res.send(users);
+});
 ```
 
 This library is about what happens when you hit an error.

index.js

@@ -1,36 +1,40 @@
+'use strict';
+
+const { IncomingMessage, ServerResponse } = require('http');
+const co = require('co');
 const Layer = require('express/lib/router/layer');
-const Router = require('express/lib/router');
+const { Router } = require('express');
 
-const last = (arr = []) => arr[arr.length - 1];
-const noop = Function.prototype;
+// eslint-disable-next-line no-empty-function
+const GeneratorFunction = (function* () {}).constructor;
 
-function copyFnProps(oldFn, newFn) {
-  Object.keys(oldFn).forEach((key) => {
-    newFn[key] = oldFn[key];
-  });
-  return newFn;
+const isError = (arg) => arg instanceof Error;
+const isGeneratorFunction = (arg) => arg instanceof GeneratorFunction;
+const isRequest = (arg) => arg instanceof IncomingMessage;
+const isResponse = (arg) => arg instanceof ServerResponse;
+const noop = () => {};
+
+function copyProps(source, dest) {
+  return Object.keys(source).reduce((acc, key) => {
+    const value = source[key];
+    return Object.assign(acc, { [key]: value });
+  }, dest);
 }
 
 function wrap(fn) {
   const newFn = function newFn(...args) {
+    if (isGeneratorFunction(fn)) fn = co.wrap(fn);
     const ret = fn.apply(this, args);
-    const next = (args.length === 5 ? args[2] : last(args)) || noop;
-    if (ret && ret.catch) ret.catch(err => next(err));
+    const predicates = [isError, isRequest, isResponse];
+    const next = args.find((arg) => predicates.every((match) => !match(arg))) || noop;
+    if (ret && ret.catch) ret.catch((err) => next(err));
     return ret;
   };
   Object.defineProperty(newFn, 'length', {
     value: fn.length,
     writable: false,
   });
-  return copyFnProps(fn, newFn);
-}
-
-function patchRouterParam() {
-  const originalParam = Router.prototype.constructor.param;
-  Router.prototype.constructor.param = function param(name, fn) {
-    fn = wrap(fn);
-    return originalParam.call(this, name, fn);
-  };
+  return copyProps(fn, newFn);
 }
 
 Object.defineProperty(Layer.prototype, 'handle', {
@@ -44,4 +48,8 @@ Object.defineProperty(Layer.prototype, 'handle', {
   },
 });
 
-patchRouterParam();
+const originalParam = Router.prototype.constructor.param;
+Router.prototype.constructor.param = function param(name, fn) {
+  fn = wrap(fn);
+  return originalParam.call(this, name, fn);
+};