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Why are frontend frameworks in NPM?

When I’m looking at some github projects and tutorials I look at the package.json file and see frontend frameworks listed as the dependencies quite a lot. I don’t get it. I thought Node was backend? My understanding is that to install frontend frameworks you dl them directly from their website or github or use a CDN then link them in your pages - all this has nothing to do with Node.
Even if I did install a framework through Node doesn’t it save it to the node_modules folder? There must be a reason for it as I’ve seen a lot of projects list them in their package.json file. Can anyone explain this to me?

NodeJS is not only a "server" in the sense that it is a programmable webserver, it is a JavaScript runtime. You can use it to serve webpages, but you can also use the NodeJS server as a parser / generator for JavaScript (meaning: reading and writing files on the system). If you use one of the frontend frameworks like react and angular, you install the packages just to get their sourcecode and not to actually run the code on the server. Then you use a bundler like webpack to turn the code you've written and the code from the modules into one (or multiple) large chunks of minified frontend code. You can usually find those generated files inside the /dist or /build folder. Now to get these files to clients, you can use NodeJS as a server too, serving the files to the clients. That way, the packages "installed" on your server end up on your client.

Can we use angular without node?

We are working with Django as a server framework and used JavaScript for client-side scripting. Now we are migrating to Angular4, do we need to run a node.js server with the existing running Django server?

No, Angular is basically concerned with your front-end in your case, you don't need to use Node together with Django for your back-end.
However, what you would need node for is the build process and dependencies, as Node helps in the building process of your Angular project and in the management of your dependencies, this is facilitated also with NPM.
Apart from that, Node also allows you use the port:4200 when serving using ng serve.... Once your project passes the development stage and you have a dist folder, you don't need the ng serve process anymore and the files within the folder are static and can be run like your normal index.html files...
I do hope this is helpful.

Angular is for your front-end. You can use what you want for the back-end.
You can use Node to build your sources, to convert typescript files to javascript files.

How to use NPM Modules with Flask?

I have a python application which I am deploying through Flask using the render_template() function onto a webpage. At the same time, I am trying to use npm to incorporate some javascript modules into my code. Whilst I have correctly installed the needed modules within the static folder with all my other javascript files, the code refuses to recognize these modules.
My Flask CLI shows that my local development server has correctly located the module file but if I run var module = require('module') the code shows no indication of having worked if run through the browser. This goes for whether I include this script inside my html template in the template folder, or an external javascript file in the static folder.
Interestingly enough, if I run the same external javascript file through the npm CLI using node script.js, the script will execute. Can someone explain what I'm doing wrong and why this is so? I'm completely new to node.js, npm and have just started today so any help would be appreciated.
I am currently basing my work off of the answer with 6 upvotes here: How can I serve NPM packages using Flask?

You can use electron as the ui for the python app by spawning your file and navigating to the local url in the app instead of using a browser. With this you will have some node capability.

Without knowing more, this is a bit of a stab in the dark, and quite late, however, I solved a similar problem with the following:
app = Flask(__name__,
static_folder = './public',
template_folder="./static")

npm is. Node.js packages manager tool. And it is only used node.js application.
If your application frontend is react or vue framework and your backend is node.js framework example Express or Koa, use npm is good. but now your backend is Flask
, you know Python package manage tools is Pip, so if you use Npm, you should use node in frontend , backend is flask, and frontend start npm start, backend start python app.py.

Maven Profile concept in a NodeJS Project without MVN

Hello stakOverFlowers :D
I have a simple NodeJS WebApp that use Lerna to manage the project. So i have a package directory that contains n different projects each ones using different tasks runner tools.
I always use Maven Build Profile in java environment but for this NodeJS project maven will not be used.
So the question is...
Is there a way to reproduce the Maven Build Profile concept without using MVN?
In a nutshell i need to use a build profile in nodejs, without using MVN, to customize build for different environments such as Production v/s Development environments.
There's a way to do that?
thanks to all

you can do it by storing your configurations in a JSON file as key value pairs in the same way as you do in properties file in Java.
Then by someway or other invoke properties from the environment specific configuration file such as production.json or stage.json or qa.json.
One of the easy ways to do this is using this module named config
Using this you can pass NODE_ENV=production(or dev or qa whatever) and access relevant configurations. This will help you achieve environment profiling.
You can also store configurations in a JS file but I personally prefer a JSON file for storing configurations.
But if you're wondering for dependencies management that is done by package.json file which is somewhat similar to your pom.xml file.
For more details about it you might want to read this official documentation for it.

My solution, following the TGW advice, works!!
Just install the config module, and create a directory that containing .json files.
$ npm install config
$ mkdir config
$ vi config/default.json
Than if u are on a windows machine, choose your NODE_ENV using NODE_ENV=production and than execute your web app.
In your .js file put informations like yours dbConnection host and password.... and to retrieve it use:
var config = require('config');
var dbConfig = config.get('JsonItem.dbConfig');
..more details on https://github.com/lorenwest/node-config

How do I reference a js file from a node module in HTML?

I've used JetBrains WebStorm to create a Node.js Express App. I used npm (via File->Settings->Node.js and NPM) to install a package called validator which is used for string validation.
The package was installed under node_modules, which is fine. If I do var validator = require('validator'); in my server code, I can use the validation functions successfully.
The problem is that I would also like to use validator in client JavaScript. I can include the script like this:
<script src="/javascripts/xss-filters.min.js"></script>
But that means I have to copy xss-filters.min.js from the node_modules folder into the public javascripts folder. Then, if I ever update the package with npm, the files will be out of sync.
Is there some way to reference node_modules from my view, or to create some sort of linked file or file reference or something? I'd rather not have to maintain this manually.

you should consider using browserify, which allows you to require modules in the browser by building all the dependencies. so basically you code like you would do in server side http://browserify.org

You can done it by using another node.js module, called node-browserify
how to use node.js module system on the clientside
You can try to use bower, or yeoman.
bower - will simplify the process to include js libs.
yeoman - will help you to build projects with the the libraries that you need.