Flow Middleware | Run any Of Express Middlewares on Next.js

Flow Middleware

Run Express middlewares on any Node.js server framework without hacking/polluting native req/res objects with Proxy.

Why, How

Why

As people start using a new Node server library other than Express, they encounter a lack of middlewares that Express already has, which have been well tested and production-ready many years ago. Some of them try to shape a brand new ecosystem on the new island and some just go back to Express.

Let's start from admitting Express is one of the most successful, beautifully designed and battle-tested software in the Node ecosystem. Don't forget its hundreds of outstanding middlewares have been born on it. Then why you can't use them? The answers will be summarized:

  • It breaks since they depend on req.param() and res.redirect() that Express decorates native objects with. I don't want to hack to make them work in my ${Your favorite server comes here}.
  • Pollution. Express officially recommends middlewares to extend object properties such as req.session and req.flash, just where my ${Your favorite server} leaves them tidy. Plus, dynamic extensions don't fit today of the TypeScript era.

Yeah. Let's move on.

How

JavaScript Proxy.

Wrapping req and res by Proxy to split using native methods and Express methods. Express exports clean prototypes that we can intercept internal calls with. It lets middlewares to call native methods like res.writeHead() and res.end() so native objects properly embed HTTP info and send the response.

In the end, flow-middleware returns the extended properties like req.session and req.user so you can use them after the middlewares go through.

Getting started

Install it with Express.

yarn add flow-middleware express

flow(...middlewares)

A function flow creates an http handler from some Express middlewares, processed from left to right of arguments.

import flow from 'flow-middleware';
import { ok } from "assert";
import { createServer } from 'http';
import cookieParser from 'cookie-parser';
import session from 'express-session';
import flash from 'express-flash';

// Creates an async function that handles req and res.
const handle = flow(
    cookieParser(),
    session({ secret: 'x' }),
    flash(),
    (reqProxy, _resProxy, next) => {
    
        // Our wrapped objects provide accessors
        // that Express middlewares extended💪
        ok(reqProxy.cookies);
        ok(reqProxy.session);
        ok(reqProxy.flash);
        next();
    }
);

createServer(async (req, res) => {
  
    // Let's run the Express middlewares🚀
    const [ reqProxy, resProxy ] = await handle(req, res);

    // Native objects are clean thanks to our proxy✨
    ok(req.cookies === undefined);
    ok(req.session === undefined);
    ok(req.flash === undefined);

    // You still can access to Express properties here🚚
    ok(reqProxy.cookies);
    ok(reqProxy.session);
    ok(reqProxy.flash);
    ok(resProxy.cookie);
    ok(resProxy.redirect);

    res.end('Hello!');
}).listen(3000);

compose(...middlewares)(...middlewares)()

compose lets you hold a set of middlewares and share it on other routes. This is useful when you want the same initializing middlewares to come first while the different middlewares come at the end. Calling it with zero arguments returns a handler function.

This is a Passport example where a login handler for POST /api/auth/github and an OAuth callback handler for GET /api/auth/callback/github share their initializing middlewares.

import cookieSession from 'cookie-session';
import { compose } from 'flow-middleware';
import passport from './passport';

const composed = compose(
    cookieSession(),
    passport.initialize(),
    passport.session()
);

const handleToLogIn = composed(passport.authenticate('github'))();

const handleForCallback = composed(passport.authenticate('github', {
    failureRedirect: '/auth',
    successRedirect: '/',
}))();

Don't forget to call it with zero arguments at last to get a handler.

Wrapper function style

Or, you can simply write a wrapper function to share middlewares.

import { Handler } from 'express';

function withPassport(...middlewares: Handler[]) {
    return flow(
        cookieSession(),
        passport.initialize(),
        passport.session(),
        ...middlewares
    );
}

Learn More

Checkout the Next.js example with Passport.js integration.

Download Details:
Author: piglovesyou
Source Code: https://github.com/piglovesyou/flow-middleware
License:

#nextjs #react #javascript

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Flow Middleware | Run any Of Express Middlewares on Next.js

NBB: Ad-hoc CLJS Scripting on Node.js

Nbb

Not babashka. Node.js babashka!?

Ad-hoc CLJS scripting on Node.js.

Status

Experimental. Please report issues here.

Goals and features

Nbb's main goal is to make it easy to get started with ad hoc CLJS scripting on Node.js.

Additional goals and features are:

  • Fast startup without relying on a custom version of Node.js.
  • Small artifact (current size is around 1.2MB).
  • First class macros.
  • Support building small TUI apps using Reagent.
  • Complement babashka with libraries from the Node.js ecosystem.

Requirements

Nbb requires Node.js v12 or newer.

How does this tool work?

CLJS code is evaluated through SCI, the same interpreter that powers babashka. Because SCI works with advanced compilation, the bundle size, especially when combined with other dependencies, is smaller than what you get with self-hosted CLJS. That makes startup faster. The trade-off is that execution is less performant and that only a subset of CLJS is available (e.g. no deftype, yet).

Usage

Install nbb from NPM:

$ npm install nbb -g

Omit -g for a local install.

Try out an expression:

$ nbb -e '(+ 1 2 3)'
6

And then install some other NPM libraries to use in the script. E.g.:

$ npm install csv-parse shelljs zx

Create a script which uses the NPM libraries:

(ns script
  (:require ["csv-parse/lib/sync$default" :as csv-parse]
            ["fs" :as fs]
            ["path" :as path]
            ["shelljs$default" :as sh]
            ["term-size$default" :as term-size]
            ["zx$default" :as zx]
            ["zx$fs" :as zxfs]
            [nbb.core :refer [*file*]]))

(prn (path/resolve "."))

(prn (term-size))

(println (count (str (fs/readFileSync *file*))))

(prn (sh/ls "."))

(prn (csv-parse "foo,bar"))

(prn (zxfs/existsSync *file*))

(zx/$ #js ["ls"])

Call the script:

$ nbb script.cljs
"/private/tmp/test-script"
#js {:columns 216, :rows 47}
510
#js ["node_modules" "package-lock.json" "package.json" "script.cljs"]
#js [#js ["foo" "bar"]]
true
$ ls
node_modules
package-lock.json
package.json
script.cljs

Macros

Nbb has first class support for macros: you can define them right inside your .cljs file, like you are used to from JVM Clojure. Consider the plet macro to make working with promises more palatable:

(defmacro plet
  [bindings & body]
  (let [binding-pairs (reverse (partition 2 bindings))
        body (cons 'do body)]
    (reduce (fn [body [sym expr]]
              (let [expr (list '.resolve 'js/Promise expr)]
                (list '.then expr (list 'clojure.core/fn (vector sym)
                                        body))))
            body
            binding-pairs)))

Using this macro we can look async code more like sync code. Consider this puppeteer example:

(-> (.launch puppeteer)
      (.then (fn [browser]
               (-> (.newPage browser)
                   (.then (fn [page]
                            (-> (.goto page "https://clojure.org")
                                (.then #(.screenshot page #js{:path "screenshot.png"}))
                                (.catch #(js/console.log %))
                                (.then #(.close browser)))))))))

Using plet this becomes:

(plet [browser (.launch puppeteer)
       page (.newPage browser)
       _ (.goto page "https://clojure.org")
       _ (-> (.screenshot page #js{:path "screenshot.png"})
             (.catch #(js/console.log %)))]
      (.close browser))

See the puppeteer example for the full code.

Since v0.0.36, nbb includes promesa which is a library to deal with promises. The above plet macro is similar to promesa.core/let.

Startup time

$ time nbb -e '(+ 1 2 3)'
6
nbb -e '(+ 1 2 3)'   0.17s  user 0.02s system 109% cpu 0.168 total

The baseline startup time for a script is about 170ms seconds on my laptop. When invoked via npx this adds another 300ms or so, so for faster startup, either use a globally installed nbb or use $(npm bin)/nbb script.cljs to bypass npx.

Dependencies

NPM dependencies

Nbb does not depend on any NPM dependencies. All NPM libraries loaded by a script are resolved relative to that script. When using the Reagent module, React is resolved in the same way as any other NPM library.

Classpath

To load .cljs files from local paths or dependencies, you can use the --classpath argument. The current dir is added to the classpath automatically. So if there is a file foo/bar.cljs relative to your current dir, then you can load it via (:require [foo.bar :as fb]). Note that nbb uses the same naming conventions for namespaces and directories as other Clojure tools: foo-bar in the namespace name becomes foo_bar in the directory name.

To load dependencies from the Clojure ecosystem, you can use the Clojure CLI or babashka to download them and produce a classpath:

$ classpath="$(clojure -A:nbb -Spath -Sdeps '{:aliases {:nbb {:replace-deps {com.github.seancorfield/honeysql {:git/tag "v2.0.0-rc5" :git/sha "01c3a55"}}}}}')"

and then feed it to the --classpath argument:

$ nbb --classpath "$classpath" -e "(require '[honey.sql :as sql]) (sql/format {:select :foo :from :bar :where [:= :baz 2]})"
["SELECT foo FROM bar WHERE baz = ?" 2]

Currently nbb only reads from directories, not jar files, so you are encouraged to use git libs. Support for .jar files will be added later.

Current file

The name of the file that is currently being executed is available via nbb.core/*file* or on the metadata of vars:

(ns foo
  (:require [nbb.core :refer [*file*]]))

(prn *file*) ;; "/private/tmp/foo.cljs"

(defn f [])
(prn (:file (meta #'f))) ;; "/private/tmp/foo.cljs"

Reagent

Nbb includes reagent.core which will be lazily loaded when required. You can use this together with ink to create a TUI application:

$ npm install ink

ink-demo.cljs:

(ns ink-demo
  (:require ["ink" :refer [render Text]]
            [reagent.core :as r]))

(defonce state (r/atom 0))

(doseq [n (range 1 11)]
  (js/setTimeout #(swap! state inc) (* n 500)))

(defn hello []
  [:> Text {:color "green"} "Hello, world! " @state])

(render (r/as-element [hello]))

Promesa

Working with callbacks and promises can become tedious. Since nbb v0.0.36 the promesa.core namespace is included with the let and do! macros. An example:

(ns prom
  (:require [promesa.core :as p]))

(defn sleep [ms]
  (js/Promise.
   (fn [resolve _]
     (js/setTimeout resolve ms))))

(defn do-stuff
  []
  (p/do!
   (println "Doing stuff which takes a while")
   (sleep 1000)
   1))

(p/let [a (do-stuff)
        b (inc a)
        c (do-stuff)
        d (+ b c)]
  (prn d))
$ nbb prom.cljs
Doing stuff which takes a while
Doing stuff which takes a while
3

Also see API docs.

Js-interop

Since nbb v0.0.75 applied-science/js-interop is available:

(ns example
  (:require [applied-science.js-interop :as j]))

(def o (j/lit {:a 1 :b 2 :c {:d 1}}))

(prn (j/select-keys o [:a :b])) ;; #js {:a 1, :b 2}
(prn (j/get-in o [:c :d])) ;; 1

Most of this library is supported in nbb, except the following:

  • destructuring using :syms
  • property access using .-x notation. In nbb, you must use keywords.

See the example of what is currently supported.

Examples

See the examples directory for small examples.

Also check out these projects built with nbb:

API

See API documentation.

Migrating to shadow-cljs

See this gist on how to convert an nbb script or project to shadow-cljs.

Build

Prequisites:

  • babashka >= 0.4.0
  • Clojure CLI >= 1.10.3.933
  • Node.js 16.5.0 (lower version may work, but this is the one I used to build)

To build:

  • Clone and cd into this repo
  • bb release

Run bb tasks for more project-related tasks.

Download Details:
Author: borkdude
Download Link: Download The Source Code
Official Website: https://github.com/borkdude/nbb 
License: EPL-1.0

#node #javascript

Fleta  Dickens

Fleta Dickens

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Serve CSS JS and Images Files in Express JS | Use Middleware in Express | express.static

#stubborndevelopers
In this video we will learn below points:

  1. how we can use css, js and images in website created using express js in Node.js?
  2. how we can use inbuilt middleware app.use(express.static()) of express JS?

************ Node.JS Tutorial in English 2021 Playlist ************
https://www.youtube.com/watch?v=gs0X92Yx70s&list=PLllIEssCHLKdNEVWsBQ5zcCxLu8Xpsl0E&index=2

************ React.JS Tutorial in Hindi 2021 Playlist ************
https://www.youtube.com/watch?v=F2A1qXcskP8&list=PLllIEssCHLKdRqOrDJdPIeW7nrwPPfa46

#node.js #express.stati #css #js #express js

Eva  Murphy

Eva Murphy

1625674200

Google analytics Setup with Next JS, React JS using Router Events - 14

In this video, we are going to implement Google Analytics to our Next JS application. Tracking page views of an application is very important.

Google analytics will allow us to track analytics information.

Frontend: https://github.com/amitavroy/video-reviews
API: https://github.com/amitavdevzone/video-review-api
App link: https://video-reviews.vercel.app

You can find me on:
Twitter: https://twitter.com/amitavroy7​
Discord: https://discord.gg/Em4nuvQk

#next js #js #react js #react #next #google analytics

Eva  Murphy

Eva Murphy

1625751960

Laravel API and React Next JS frontend development - 28

In this video, I wanted to touch upon the functionality of adding Chapters inside a Course. The idea was to not think much and start the development and pick up things as they come.

There are places where I get stuck and trying to find answers to it up doing what every developer does - Google and get help. I hope this will help you understand the flow and also how developers debug while doing development.

App url: https://video-reviews.vercel.app
Github code links below:
Next JS App: https://github.com/amitavroy/video-reviews
Laravel API: https://github.com/amitavdevzone/video-review-api

You can find me on:
Twitter: https://twitter.com/amitavroy7​
Discord: https://discord.gg/Em4nuvQk

#next js #api #react next js #next #frontend #development

Eva  Murphy

Eva Murphy

1625696280

Next JS Registration Flow Completed with Formik and Yup Validation - 19

In this video, we are going to look at the complete code for the registration of the user. We will see how the integration works where a user is registering to the application and then gets an email to verify the email account.

Once the email link is clicked. the user is verified and redirected to the Dashboard.

Frontend: https://github.com/amitavroy/video-reviews
API: https://github.com/amitavdevzone/video-review-api
App link: https://video-reviews.vercel.app

You can find me on:
Twitter: https://twitter.com/amitavroy7​
Discord: https://discord.gg/Em4nuvQk

#next js #next #yup #formik #registration flow