koa-to-express

Use a Koa/Express middleware in an Express/Koa app.

It could convert a middleware to another form between Express and koa middleware.

Requirement

Koa-to-express requires koa@2.0.0 and express@4.0.0 or higher.

Node 7.6+ is required if you want to use ES2015’s async/await syntax.

Please go to koa-to-express@1.x if you want to use koa1.

Installation

Npm 5.x

npm install koa-to-express [-P]

Others

npm install koa-to-express -S

Usage

const k2e       = require('koa-to-express');
const koaMiddleware = (ctx, next) => {
    ctx.body = 'hello world';
    return next();
};
require('express')().use(k2e(koaMiddleware)).listen(3000);
// curl localhost:3000/
// output: hello world

API

koaToExpress[.koaToExpress](middleware)

• middleware : Function|Array<Function>

• Convert Koa middleware(s) into an Express middleware and return it.

• Note that the second parameter (usually named as “next”) passed to the last one of the middlewares is () => Promise.resolve(), because the cascading categories between Koa and Express are different and the end of the rest Express middlewares executing can’t be informed back.

• It means that, resolving or rejecting the Koa middleware(s), which will return a resolved or rejected promise, will call the next middleware (as calling the Express’s next()) or throw out an error (as calling the next(err)).

koaToExpress.expressToKoa(middleware)

• middleware : Function|Array<Function>

• Convert Express middleware(s) into a Koa middleware and return it.

License

MIT