Develop Reference

Setting up server.js

I am trying to containerize my React application with docker and am now a little bit stuck with the server.js file as I do not know how to "implement" the application inside. I was able to simply show a "Hello World" but can't seem to run the application inside.
My idea was initially, that I could just use the index.js file as an entrypoint and use it in the "res.end(x)" as this was the place where I could simply enter the "Hello World".
Am I missing just something small or is my general approach wrong?
My server.js file looks as followed:
const http= require('http');
const fs = require('fs');
const index = fs.readFileSync('index.js');
let app = http.createServer((req, res) => {
res.writeHead(200,{'Content-Type': 'text/plain'});
res.end(index);
});
app.listen(9030, '0.0.0.0');
console.log('Node server running on port 9030')

I share with you this best documentation :
https://nodejs.org/en/docs/guides/nodejs-docker-webapp/

React is generally coded in .jsx files, which need to be compiled/transpiled into regular Javascript. Once this is done, you can serve these files to web browsers any way you like.
Understanding Build tools
React compilation/transpilation is done using Webpack or Parcel. If you're using Create-React-App, then you're using Webpack under the hood. CRA npm start will run a Webpack dev server, and npm run build will put all of the files you need in your build directory. You should do the latter if you want to
Avoid using Webpack dev server
Most tutorials, including the one linked in the comments, suggest using Webpack development server (aka npm start) to run your server in Docker. which is not recommended. Not only does it consume more resources to run, but the development build will run slower in browsers than the production build. The development server is also not meant to handle heavy loads.
Use build for production, with a real server
Use npm run build to generate the build files in the build directory, then use a real web server to serve them to the world.
One example in Docker, using Nginx to serve the files, can be found here
Alternatively the CRA build command itself offers a helpful hint:
The build folder is ready to be deployed.
You may serve it with a static server:
npm install -g serve
serve -s build
This will work in a Docker Node container. An example of a very not-optimized Dockerfile might look like this
FROM node:16-alpine
COPY . .
RUN npm install
RUN npm build
RUN npm install -D serve
CMD ["./node_modules/.bin/serve", "-s", "build"]
The build process can be improved here to leverage cache (by first copying package.json and package-lock.json and installing before copying code over, see example at the end of the answer here), and all of the RUN commands combined

Configuring Express Generator to use Pug instead of Jade

I installed Express Generator for Node.js but when I created an example app, I noticed that Jade is deprecated to Pug. I installed Pug, but I still need to tell express generator to use it each time. I've been reading about the subject and it's telling developers to just change the file names manually, but is there a way for this to work out of the box? How do I do that?

Express defaults to Jade but if you wish to pug as a template engine instead of using Jade.
You must type
express --view=pug myapp
This will create a new application called "myapp" using pug by default.
For a more in dept explanation type
express -h
this will show you the available commands, one of the commands is -v
--view add view support
Reference: https://expressjs.com/en/starter/generator.html

I made two mistakes trying to follow the above docs. It's because I'm still getting used to installing packages locally and globally.
2 Mistakes:
I. npx express-generator
This installed it locally, making express unavailable in the command line terminal.
When I installed it globally, I had access.
II. starting in a folder on Atom, an IDE. Express-generator creates a folder for you, so you start in the terminal outside of a folder, such as your desktop.
9 Steps to solution:
Use the terminal in your desktop directory, not an IDE.
Do not create a folder or any file.
Install express-generator globally, not locally.
sudo npm express-generator
Verify you have access by: express -h
Type: express --view=pug my app
Change directories to myapp folder on desktop
npm install
DEBUG=myapp:* npm start
open your browser to http://127.0.0.1:3000/

I think this issue come when npx express-generator is used alone (for those who have node versions above Node.js 8.2.0).
for node versions 8.2.0 or above,
Navigate to the directory where you want to create the app
npx express-generator --view=pug myapp
This will create a myapp folder in the directory with required .pug
files instead of .jade files
for earlier node versions you can find the required steps here express
application generator documentation

npx express-generator --view=pug install.
this should do the trick

Not Getting $ in command prompt in Node.Js

My NodeJs is working fine but i have an issue I'm not seeing $ in the prompt as most example point.
Another issue is when i put sudo I dont get anything.Things I have tried are the following
$ sudo npm install npm -g
/usr/bin/npm -> /usr/lib/node_modules/npm/bin/npm-cli.js
npm#2.7.1 /usr/lib/node_modules/npm
given on the following Website
http://www.tutorialspoint.com/nodejs/nodejs_npm.htm
Apologies am very new to Node.JS.Please help

I'm going to explain this in terms familiar to MS windows.
$ npm --version
^ dollar sign is the same as "C:\" in windows.
It just means "from here..." in the most basic terms I can use.
You don't need the dollar sign for anything in that tutorial.
"sudo" means "elevate to an administrator level" similar to opening a command line terminal "in administrator mode." But for Linux (Ubuntu and Mac as *NIX) systems.
--version can be called as "-v" most of the time and means "for the thing I've named before, in this case "npm" show me the version.
Once you've installed NodeJS it comes with a "package manager" called NPM. The best way to relate this to windows is by considering it a command line version of an "installation" that installs different programs as you tell it to with different options.
"npm install -g" means "Hey NPM! Install to EVERYWHERE(call from command line/terminal/bash) the thing I Tell you next. "npm install -g express" for example, means hey NPM, install "expressJS" globally, so I can use the terminal to write commands(micro apps) from the expressJS I just installed with node.
"npm install --save" means hey, install this microapp, but ONLY let me use it in THIS EXACT FOLDER I'm in, and let anyone else that is in this folder know they need to install it to use this application I'm making.
"npm init" Is actually the FIRST thing you should do in any node project folder. It creates the "package.json" file in the current directory, and it will define the folder you're in as the folder to start installing stuff you "npm install" to the "node_modules" folder that will show in the folder you're currently in.
If you want to tinker with NodeJS code, and you don't want to tamper with your local machine and install all kinds of stuff you're not totally sure about yet you can use "REPL.it" (https://repl.it/languages/nodejs) the white window on the right is treated like a file you'd run in node. The dark window on the right is an actual NODE TERMINAL that you can run nodejs commands/code in directly.
There's one other good resources in general and that is here (https://devdocs.io/) it's called "Devdocs" and it has Node, npm, and express code examples, clean explanations, and examples that you can download directly to your local machine.
I hope that gets you moving with NodeJS. It's hard to understand, but with a bit of try and fail you'll start to try more and fail less. Cheers!

can not find module express --on windows

I use "npm install -g express" on windows console.but when I try to "node app.js", it shows me the error"can not find module express",I had set the environment variable"NODE_PATH",but nothing happen ,I need your help,Thank you!

Globally installed modules aren't accessible without full path. You need to install express in your project directory or it parents. Check out documentation about module loading.

npm allows two options on how to install a module: locally and globally.
A global installation (done using npm install -g xyz) is for providing some tooling system-wide. Related to express this provides the global express bootstrapper that you can use to create an initial frame for your app by simply typing: express .. If you need help on what you can do with this command, check out its help parameter: express --help.
In contrast, a local installation of a module provides this module for a specific app. A local installation is always made to an app's node_modules folder. When you try to require a module, Node.js searches the this folder for the requested module.
Hence, it is perfectly fine to have express installed multiple times: Once globally for the bootstrapper, multiple times locally (once per app).
So, to cut a long story short: To make your app run, install express locally using npm install express and that's it :-).

WebStorm, using Node Supervisor (so do not have to restart after each code change)?

I'm using WebStorm as my node IDE and love it overall but I haven't been able to figure out how to use node supervisor when running node through WebStorm. Has anyone gotten this to work? I think I'm just not sure how to pass through the supervisor argument so that it uses this when starting the node file.

Install supervisor globally:
npm install -g supervisor
WebStorm/IntelliJ run configuration for non-debug:
Name: supervisor app.js
Path to node: <same>
Node Parameters: /usr/local/lib/node_modules/supervisor/lib/cli-wrapper.js --exec /usr/local/bin/node --no-restart-on exit
Working directory: <same>
Path to Node App JS File: app.js
These paths are for Mac OS X 10.8 so you'll have to replace the above paths with paths on your machine. Next, you'll be able to run this in debug mode but it doesn't step through the code.
For debugging you can either use the remote debugger or just have a different run target for debugging without using supervisor.

It is amazing that I reach the goal by simply changing the path of node to the path of supervisor. So, I think this will also work for you.
Ps. I'm using WebStorm version 6.0.1.