Use Express/Connect middleware with Koa v2.
It is highly recommended to use a Koa-specific middleware instead of trying to convert an Express version when they're available. There is a non-trivial difference in the Koa and Express designs and you will inevitably run into some issues. This module is a workaround for the specific cases where the differences can be ignored. Additionally, it also enables library authors to write 1 version of their HTTP middleware.
Express middlewares need to declare and invoke the next callback appropriately for the koa-connect integration to work correctly.
If you're attempting to write a framework-agnostic middleware library, be sure to use only core HTTP methods and not any Express-dependent APIs like res.send.
npm install koa-connect@nextSee examples/ for more real-world examples.
const Koa = require('koa')
const c2k = require('koa-connect')
// A generic Express-style middleware function
function connectMiddlware (req, res, next) {
res.writeHead(200, {'Content-Type': 'text/plain'})
res.end('From the Connect middleware')
next()
}
// A generic Koa v2 middlware, without async/await
function koaMiddlware(ctx, next) {
next()
.then(() => {
// The control flow will bubble back to here, like usual
})
.catch((err) => {
// Error handling from downstream middleware, like usual
})
}
// A generic Koa v2 middlware with async/await
async function koaMiddleware(ctx, next) {
try {
await next();
} catch (e) {
// Normal error handling
}
// Normal control flow
}
const app = new Koa()
app.use(koaMiddlware)
app.use(c2k(connectMiddlware))
app.use((ctx, next) => {
console.log('It will continue on to here')
})
app.listen(3000)Tests are in tests.js and are made with the Mocha framework. You can run them with npm test or npm run test:watch
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