njseries_02_04.js

class Router {
    ...

    _dispatch(request, response){
        let match, handledRequest = false, {url} = request
        for(let route of this._routes){
            // 1- Keep trying  till we find a match 
            match = url.match(route.regex)
            if(match === null || !route.methods.includes(request.method)){
                continue
            }

            // 2- Collect route params value when match found 
            match = match.filter(item => {
                return !item || !item.startsWith('/')
            })
            request.params = route.params.reduce((obj, param, idx) => {
                obj[param] = match[idx]
                return obj
            }, {})

            // 3- Create handler chain and start processing request
            let nextHandler
            const handlerStack = route.handlers.slice().reverse()
            const params = Object.values(request.params)
            for(const handler of handlerStack){
                let lastNext = nextHandler
                const next = () => {
                    handler(request, response, lastNext, ...params)
                }
                nextHandler = next
            }
            nextHandler()
            handledRequest = true
            break;
        }

        if(handledRequest){
            return
        }
        response.statusCode = 404;
        response.end("Not Found !")
    }

    ...
}