Simple middleware implementation using typescript and ES6

index.ts

import pipeline, { Middleware } from './pipeline';

const step1: Middleware<any, any> = (req, res, next) => {
    if (req.body) {
        console.log(`STEP 1: \n req: ${JSON.stringify(req)}\n res: ${JSON.stringify(res)}`);
        next();
    }
}

const step2: Middleware<any, any> = async (req, res, next) => {
    await setTimeout(() => {
        res.status = 200;
        console.log(`STEP 2: \n req: ${JSON.stringify(req)}\n res: ${JSON.stringify(res)}`);
        next();
    }, 2000);
}

const step3: Middleware<any, any> = (req, res, next) => {
    console.log(`STEP 3: \n req: ${JSON.stringify(req)}\n res: ${JSON.stringify(res)}`);
    next();
}

const req = { body: {}};
const res = {};

pipeline(req, res, step1, step2, step3);

pipeline.ts

export type Middleware<T, P> = (req: T, res: P, next: () => void) => any;

const pipeline = (req: any, res: any, ...steps: Middleware<any, any>[]) => {
    const [ step, ...next ] = steps;
    return (step) ? step(req, res, () => pipeline(req, res, ...next)) : undefined;
}

export default pipeline;