Intercept local requests to a remote server with Node.js - node.js

Using NodeJS, is it possible to listen to calls from localhost:3000 to my.site.com/resources/* and serve those files locally instead ?
Context: my Angular app relies on resources from a CDN. Sometimes when the CDN is down, I want to serve these files locally.

You can use javascript to check if angular object is correctly loaded , if not you generate a new tag a local link instead of CDN
<script src="//cdn_link/angular.min.js"></script>
<script>
(typeof angular != 'undefined') || document.write('<script src="local_link/angular.min.js")<\/script>')
</script>
For angular2 you can check for ng object instead of angular

Related

Is it possible to serve React from Node?

I'm new to back-end coding, and I'm struggling to understand exactly what a "fullstack" app would look like.
Is it:
A Node-Express server that serves index.html, which has <script src="main.jsx"></script> in it (If this is the case, how would the .jsx content get compiled into browser-ready javascript?)
A Node-Express server that serves some data (.json) + a frontend app (that you would initialize with Vite or CRA) that fetches from said server?
Both are currect , your server can serve content to the cliend (first case) or send data to the client (json , xml or etc).
Note that when you are working with react and .jsx component you have to build your project and server the html file (including js , css) via express server

How can I connect my NodeJS/Express backend to my VueJS frontend using only one port on my local machine?

My Vue app is set up using Vue CLI (Webpack) and it's working as it should. My NodeJS/Express REST API is also working properly. However, to run them simultaneously I now start a local server for each of them -- each with its own port. I would like to have both of them communicate over one port.
Localhost:8080 should point to the home page of my Vue App and the API requests should follow localhost:8080/api/...
In my production environment I use one and the same port/URL by serving the Vue App as a set of static files ('dist' folder). In my development environment I don't know how to set this up, however.
I looked around for answers online, but feel lost among all the different terms I have come across (.env, crossenv, nginx, cors) and that I am running in circles.
What would be a good way of setting this up?
Thank you
Edit:
I ended up creating three modes to run my application:
Development
I use one script in a package.json to start the frontend and backend server on different ports, using pm2 to run the servers in the 'background' rather than blocking further commands in the terminal/cmd. I use configured a proxy inside my vue.config.js to redirect my API calls made in the frontend to the right base URL and used cors as middleware to allow requests to my API from other domains/ports.
Staging
I use one script in a package.json to build the Vue app into a folder ('dist' folder inside my backend folder) that is a collection of static files and start the backend server. My backend is set up to know when I want to go into staging mode and then serve the static files in the 'dist' folder.
Production
I use one script in a package.json to build the Vue app into a folder ('dist' folder inside my backend folder) that is a collection of static files and push my backend (incl. the built static files) to Heroku.
Well if you need to run both on the same port you could first build your app so that you receive a dist directory or whatever your output directory is named and set up an express server that serves that app and otherwise handles your api requests
const express = require("express");
const path = __dirname + '/app/views/';
const app = express();
app.use(express.static(path));
app.get('/', function (req,res) {
res.sendFile(path + "index.html");
});
app.get('/api', function (req,res) {
// your api handler
}
app.listen(8080)
Assuming that node and the 'app' will always run on the same server you can just use a template library like ejs.
You would then just bundle the app and api together, assuming that the front-end is tied to the backend, realistically you would not even need to hit the API as you could just return the records as part of the view, however if dynamic elements are needed you could still hit the API.
Now, with that said, if the API is something used by many applications then it would probably make sense to build that out as its own microservice, running on its own server and your frontend would be on its own. This way you have separation of concerns with the API and Vue app.

How to connect NodeJS with ReactJS front-end

I am new to reactJS. I am working on project which uses following :
Front-end : ReactJS
Backend : NodeJS (Express)
Front-end runs on port 3000
Back-end runs on port 8088.
I am planning to deploy application on amazon AWS.
What i am trying to do is load reactJS front-end when i make request on http://localhost:8088/
I know using axios we can make request on backend server and display fetched data.
What would be standard way of loading ReactJS front from the nodeJS ?
I'm not sure if this is the answer you are looking for, but generally in development you use something called proxy in your package.json in the client (react) folder:
{
// Other stuff
"proxy": "http://localhost:8088"
}
and then when you'd want to deploy you'd run npm build for your react folder and serve that generated folder called build. But as I said, you usually do that only when deploying your application onto server, not the actual development.
Also I'd suggest checking some of these videos, that are focused on deployment, because that is what I think you are asking, right ?

node Vue.js different code scenario if run in dev mode

I have Vue.JS front app with nodeJS backend based on expressJS. ExpressJS also used as web server for statically built Vue.JS app
Front app communicates with express backend via rest and websocket. It uses url host from window.location instance and easily communicates with backend
In production mode, when built application in static expressJS server area, everything work perfect
In dev mode, Vue use it's own web server, and backend urls based on window.location are incorrect because no expresJS on same host and port.
So my question is it possible change some code blocks if running in dev mode ?
Like something this :
if( devmode)
{
const url = "http://somebackendhost/rest"
}
else {
const url = location.host ....
}
}
I will assume you are developing your Vue app using Vue CLI
Changing app behavior depending on environment
In Vue CLI you can use Environment Variables
if(process.env.NODE_ENV === "development")
{
}
This works thanks to Webpack's Define plugin and big advantage is that process.env.NODE_ENV is replaced at build time by the real value. So in production build Webpack will see just if("production" === "development") {} and happily removes the code in optimization phase because it knows this can never be true
Better solution
But I would not use this approach for your problem. Using different API server (not same as the server used for serving Vue SPA) can easily lead to CORS problems
Exactly for this use case, Vue CLI (and Webpack Dev server used under the hood) supports proxying
vue.config.js
module.exports = {
devServer: {
proxy: {
'^/api': {
target: 'http://localhost:58300/',
ws: true, // websockets
changeOrigin: true,
}
}
},
},
This config makes Vue Dev server to proxy any request to /api to other server running at http://localhost:58300/ (your node/express app) and change the origin (so browser thinks response came from the dev server)
All of this can be done without Vue CLI but you will need to set it up by yourself in Webpack config...
The problem
You can't access this information from your browser.
But there are three solutions:
Solution #1
On compilation time create a variable in code which defines devmode (const devmode = true;)
Solution #2
Because your bundler can minify your variable names or changing the scope for security reasons, may be the situation where you can't access it.
So second solution is to define devmode in your localStorage.
Solution #3
Third solution is almost the best.
If you are developing, you are probably accessing your web app via localhost.
location.hostname will return the name of host, so you can make something like:
const devmode = location.hotname == 'localhost';
Best solution
Do not do this. Develop a fully working web app using local REST API and define the URL of REST API in some variable, so when you are preparing your production app, you or compiler just changes the URL adress variable in code of your REST API.
Why is this the best solution?
Because it do not impacts your end-user's performance and they will be loading less code, which is the best practise.
Post Scriptum
Don't forget to remove all devmode codepaths when compiling production version!

How to disable users from being able to view app through regular browsers in express / electron app

I have an express server that serves my angular front end at http://localhost:9000
I'm using electron as a desktop client.
I want to force users to view the application through electron and only through electron. I don't want users to have the ability to browser the application through any other browser.
Is there any way to disable the ability to access the app through a regular browser?
I've attempted to find information regarding this but have come up short.
EDIT: This can only be done on the client side
You can check if the window.process object exists.
if (window.process && window.process !== undefined) {
// Likely electron
}
I don't know if it's related, but is it possible for you not to use localhost? I found that after building angular parts (with ng run build) and referencing them in electron's main.js there was no need for local server to be running (but so far I only stuffed angular's quickstart into electron shell)

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