<pre class="shiki github-dark shaku"><code>class Middleware { #callbacks = []; #errorHandlers = []; use(func) { if (func.length === 2) this.#callbacks.push(func) if (func.length === 3) this.#errorHandlers.push(func) } start(req) { let idx = 0; let errorIdx = 0; let func; let next = (error) =&gt; { if (error) func = this.#errorHandlers[errorIdx++].bind(this, error, req, next) else func = this.#callbacks[idx++].bind(this, req, next) try { func() } catch (err) { next(err); } } next(); }}</code></pre>

My Solution

Have you ever used Express Middleware before? Middleware functions are functions with fixed interface that could be chained up like following two func…