feat: refactor with typescript

closes eggjs/egg-core#264

.eslintrc

@@ -0,0 +1,6 @@
+{
+  "extends": [
+    "eslint-config-egg/typescript",
+    "eslint-config-egg/lib/rules/enforce-node-prefix"
+  ]
+}

Readme.md

@@ -2,13 +2,13 @@
 
 @eggjs/koa is forked from [Koa v2.x](https://github.com/koajs/koa/tree/v2.x) for LTS and drop Node.js < 16.13.0 support.
 
-<img src="/docs/logo.png" alt="Koa middleware framework for nodejs"/>
+<img height="240px" src="/docs/logo.png" alt="Koa middleware framework for nodejs"/>
 
 [![NPM version](https://img.shields.io/npm/v/@eggjs/koa.svg?style=flat-square)](https://npmjs.org/package/@eggjs/koa)
 [![NPM quality](http://npm.packagequality.com/shield/@eggjs/koa.svg?style=flat-square)](http://packagequality.com/#?package=@eggjs/koa)
 [![NPM download](https://img.shields.io/npm/dm/@eggjs/koa.svg?style=flat-square)](https://npmjs.org/package/@eggjs/koa)
 [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2Feggjs%2Fkoa.svg?type=shield)](https://app.fossa.com/projects/git%2Bgithub.com%2Feggjs%2Fkoa?ref=badge_shield)
-[![Continuous Integration](https://github.com/eggjs/koa/workflows/Continuous%20integration/badge.svg)](https://github.com/eggjs/koa/actions?query=branch%3Amaster)
+[![Node.js CI](https://github.com/eggjs/koa/actions/workflows/node.js.yml/badge.svg?branch=master)](https://github.com/eggjs/koa/actions/workflows/node.js.yml)
 [![Test coverage](https://img.shields.io/codecov/c/github/eggjs/koa.svg?style=flat-square)](https://codecov.io/gh/eggjs/koa)
 [![Known Vulnerabilities](https://snyk.io/test/npm/@eggjs/koa/badge.svg?style=flat-square)](https://snyk.io/test/npm/@eggjs/koa)
 
@@ -186,93 +186,10 @@ See [AUTHORS](AUTHORS).
 
 ## Community
 
-- [Badgeboard](https://koajs.github.io/badgeboard) and list of official modules
 - [Examples](https://github.com/koajs/examples)
 - [Middleware](https://github.com/koajs/koa/wiki) list
 - [Wiki](https://github.com/koajs/koa/wiki)
-- [Reddit Community](https://www.reddit.com/r/koajs)
-- [Mailing list](https://groups.google.com/forum/#!forum/koajs)
-- [中文文档 v1.x](https://github.com/guo-yu/koa-guide)
 - [中文文档 v2.x](https://github.com/demopark/koa-docs-Zh-CN)
-- __[#koajs]__ on freenode
-
-## Job Board
-
-Looking for a career upgrade?
-
-<a href="https://astro.netlify.com/automattic"><img src="https://astro.netlify.com/static/automattic.png"></a>
-<a href="https://astro.netlify.com/segment"><img src="https://astro.netlify.com/static/segment.png"></a>
-<a href="https://astro.netlify.com/auth0"><img src="https://astro.netlify.com/static/auth0.png"/></a>
-
-## Backers
-
-Support us with a monthly donation and help us continue our activities.
-
-<a href="https://opencollective.com/koajs/backer/0/website" target="_blank"><img src="https://opencollective.com/koajs/backer/0/avatar.svg"></a>
-<a href="https://opencollective.com/koajs/backer/1/website" target="_blank"><img src="https://opencollective.com/koajs/backer/1/avatar.svg"></a>
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-<a href="https://opencollective.com/koajs/backer/24/website" target="_blank"><img src="https://opencollective.com/koajs/backer/24/avatar.svg"></a>
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-<a href="https://opencollective.com/koajs/backer/29/website" target="_blank"><img src="https://opencollective.com/koajs/backer/29/avatar.svg"></a>
-
-## Sponsors
-
-Become a sponsor and get your logo on our README on Github with a link to your site.
-
-<a href="https://opencollective.com/koajs/sponsor/0/website" target="_blank"><img src="https://opencollective.com/koajs/sponsor/0/avatar.svg"></a>
-<a href="https://opencollective.com/koajs/sponsor/1/website" target="_blank"><img src="https://opencollective.com/koajs/sponsor/1/avatar.svg"></a>
-<a href="https://opencollective.com/koajs/sponsor/2/website" target="_blank"><img src="https://opencollective.com/koajs/sponsor/2/avatar.svg"></a>
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 # License
 

lib/application.js

@@ -1,27 +1,20 @@
-
-'use strict';
-
-/**
- * Module dependencies.
- */
-
+const debug = require('node:util').debuglog('koa:application');
+const Emitter = require('node:events');
+const util = require('node:util');
+const Stream = require('node:stream');
+const http = require('node:http');
+const { AsyncLocalStorage } = require('node:async_hooks');
 const isGeneratorFunction = require('is-generator-function');
-const debug = require('debug')('koa:application');
 const onFinished = require('on-finished');
-const assert = require('assert');
-const response = require('./response');
-const compose = require('koa-compose');
-const context = require('./context');
-const request = require('./request');
 const statuses = require('statuses');
-const Emitter = require('events');
-const util = require('util');
-const Stream = require('stream');
-const http = require('http');
+const compose = require('koa-compose');
 const only = require('only');
 const convert = require('koa-convert');
 const deprecate = require('depd')('koa');
 const { HttpError } = require('http-errors');
+const response = require('./response');
+const context = require('./context');
+const request = require('./request');
 
 /**
  * Expose `Application` class.
@@ -66,8 +59,6 @@ module.exports = class Application extends Emitter {
       this[util.inspect.custom] = this.inspect;
     }
     if (options.asyncLocalStorage) {
-      const { AsyncLocalStorage } = require('async_hooks');
-      assert(AsyncLocalStorage, 'Requires node 12.17.0 or higher to enable asyncLocalStorage');
       this.ctxStorage = new AsyncLocalStorage();
     }
   }
@@ -100,7 +91,7 @@ module.exports = class Application extends Emitter {
     return only(this, [
       'subdomainOffset',
       'proxy',
-      'env'
+      'env',
     ]);
   }
 
@@ -156,7 +147,7 @@ module.exports = class Application extends Emitter {
       if (!this.ctxStorage) {
         return this.handleRequest(ctx, fn);
       }
-      return this.ctxStorage.run(ctx, async() => {
+      return this.ctxStorage.run(ctx, async () => {
         return await this.handleRequest(ctx, fn);
       });
     };
@@ -223,7 +214,7 @@ module.exports = class Application extends Emitter {
       err instanceof Error;
     if (!isNativeError) throw new TypeError(util.format('non-error thrown: %j', err));
 
-    if (404 === err.status || err.expose) return;
+    if (err.status === 404 || err.expose) return;
     if (this.silent) return;
 
     const msg = err.stack || err.toString();
@@ -242,7 +233,7 @@ module.exports = class Application extends Emitter {
   createAsyncCtxStorageMiddleware() {
     const app = this;
     return async function asyncCtxStorage(ctx, next) {
-      await app.ctxStorage.run(ctx, async() => {
+      await app.ctxStorage.run(ctx, async () => {
         return await next();
       });
     };
@@ -255,7 +246,7 @@ module.exports = class Application extends Emitter {
 
 function respond(ctx) {
   // allow bypassing koa
-  if (false === ctx.respond) return;
+  if (ctx.respond === false) return;
 
   if (!ctx.writable) return;
 
@@ -270,7 +261,7 @@ function respond(ctx) {
     return res.end();
   }
 
-  if ('HEAD' === ctx.method) {
+  if (ctx.method === 'HEAD') {
     if (!res.headersSent && !ctx.response.has('Content-Length')) {
       const { length } = ctx.response;
       if (Number.isInteger(length)) ctx.length = length;
@@ -279,7 +270,7 @@ function respond(ctx) {
   }
 
   // status body
-  if (null == body) {
+  if (body == null) {
     if (ctx.response._explicitNullBody) {
       ctx.response.remove('Content-Type');
       ctx.response.remove('Transfer-Encoding');
@@ -299,7 +290,7 @@ function respond(ctx) {
 
   // responses
   if (Buffer.isBuffer(body)) return res.end(body);
-  if ('string' === typeof body) return res.end(body);
+  if (typeof body === 'string') return res.end(body);
   if (body instanceof Stream) return body.pipe(res);
 
   // body: json

lib/context.js

@@ -1,10 +1,3 @@
-
-'use strict';
-
-/**
- * Module dependencies.
- */
-
 const util = require('util');
 const createError = require('http-errors');
 const httpAssert = require('http-assert');
@@ -53,7 +46,7 @@ const proto = module.exports = {
       originalUrl: this.originalUrl,
       req: '<original node req>',
       res: '<original node res>',
-      socket: '<original node socket>'
+      socket: '<original node socket>',
     };
   },
 
@@ -108,7 +101,7 @@ const proto = module.exports = {
     // don't do anything if there is no error.
     // this allows you to pass `this.onerror`
     // to node-style callbacks.
-    if (null == err) return;
+    if (err == null) return;
 
     // When dealing with cross-globals a normal `instanceof` check doesn't work properly.
     // See https://github.com/koajs/koa/issues/1466
@@ -152,10 +145,10 @@ const proto = module.exports = {
     let statusCode = err.status || err.statusCode;
 
     // ENOENT support
-    if ('ENOENT' === err.code) statusCode = 404;
+    if (err.code === 'ENOENT') statusCode = 404;
 
     // default to 500
-    if ('number' !== typeof statusCode || !statuses[statusCode]) statusCode = 500;
+    if (typeof statusCode !== 'number' || !statuses[statusCode]) statusCode = 500;
 
     // respond
     const code = statuses[statusCode];
@@ -169,15 +162,15 @@ const proto = module.exports = {
     if (!this[COOKIES]) {
       this[COOKIES] = new Cookies(this.req, this.res, {
         keys: this.app.keys,
-        secure: this.request.secure
+        secure: this.request.secure,
       });
     }
     return this[COOKIES];
   },
 
   set cookies(_cookies) {
     this[COOKIES] = _cookies;
-  }
+  },
 };
 
 /**