Express-to-koa NPM

express-to-koa

Use express middlewares in Koa2 (not support koa1 for now), the one that REALLY WORKS.

Handle koa2 http status code, which fixes the common issue that we always get 404 with koa-connect
Handle express middlewares that contains .pipe(res), such as express.static which based on send

Usage

const e2k = require('express-to-koa')

// Some express middleware
const devMiddleware = require('webpack-dev-middleware')(compiler, {
  publicPath,
  quiet: true
})

const app = new Koa()
app.use(e2k(devMiddleware))

What Kind of Express Middlewares are Supported?

NEARLY ALL express middlewares built with best practices.

TL;NR

express-to-koa does not support all arbitrary express middlewares, but only for those who only uses Express-Independent APIs like res.write and res.end, i.e. the APIs that node http.ServerResponse provides.

However, if a middleware uses APIs like res.send or something, express-to-koa will do far too much work to convert those logic to koa2, which is not easier than creating both express and koa2 from 0 to 1.

So, it is a good practice to write framework-agnostic middlewares or libraries.