Develop Reference

Can svelte be compiled prior to deploying to AWS Cloudfront?

I already have API endpoints on AWS API Gateway. My use case is static delivery of an SPA built in Svelte. AWS Cloudfront would deliver the SPA to users and user behavior therein would trigger Fetch to ping the established endpoints. Under the hood, my server side APIs are all serverless, typically on Lambda. I don't want to maintain state on the server, hence the interest in an SPA.
But first things first, how do I compile Svelte into vanilla JS so that I can ship that JS bundle to Cloudfront?
From this post, there is no CLI tool to trigger compilation of Svelte->JS. I'm starting to think that I just ship the Svelte code to Cloudfront and the compilation happens under the hood...? Though this seems wrong

ReactJS Production Deployment

I currently have production web app (PHP+AngularJS) & Java/Spring backend. Basically it is a web app making lots and lots of REST Api calls to Java backend and rendering that data on web forms. I use Apache Web 2.0 to host the frontend and Tomcat for the backend
Planning to migrate to ReactJS, Java/Spring will still be the backend. I need some guidance on following
Best Web Server to use to deploy React (Build/Deploy controlled through CD/CI, Jenkins)
Any specific frameworks and/or components that needs to be added and installed to support this web app.
Best Testing framework to use for React which will work with the CI/CD pipeline.
Can all this be containerized (docker/kubernetes) ?
Thanks in advance

Any server that servers static files (express, apacha, nginx, etc) can handle a react app.
You'll need webpack to build the project (transpile/minify/optimise)
You'll need a test runner (i suggest jest from facebook) and a library to test/render you application on each unit test. Use react-testing-library (simple, dynamic and easy to use).
Totally!

Questions on NodeJS application

I have very basic questions on NodeJS apps;
When someone says a NodeJS app, does it refer to a pure server-side written NodeJS app ? I mean nowadays, when projects (say Angular, Ember, etc) use Node to install dependencies, can those client-side apps (which run in browser) be also called NodeJS app ? Or are these just NPM using apps ?
The unit-testing frameworks like Mocha, Jasmine, etc be used for both the types of apps I described above ? Or is it meant only for server-side NodeJS app ?

does it refer to a pure server-side written NodeJS app?
Yes. Specifically it refers to apps that have nodejs backend/server.
can those client-side apps (which run in browser) be also called NodeJS app?
It depends. Certain libraries that depend on browser api (e.g navigator, window, etc) will not work. This is because those browser objects will not exists in nodejs environment. For example, jQuery will not work fully in nodejs as certain functions to do with DOM manipulation depends on the browser api. On the other hand. React can be used in both browser and nodejs because it has APIs which are compatible in both browser and nodejs environment.
Previously, if we want to use a library (e.g jQuery) we'd have to attach a corresponding script tag that points to the source. Now, you can use npm to download the library code into the node_modules folder and use it from there using require or ES6 import. But, you probably have to do some preprocessing first such as bundling your code using Browserify and Gulp. You might want to look a tutorial on how to do that here.
The unit-testing frameworks like Mocha, Jasmine, etc be used for both the types of apps I described above ? Or is it meant only for server-side NodeJS app ?
Mocha, jasmine, chai does not depend on browser or nodejs specific features so they all should work in both platforms. As for the others, you have to check if they depend on browser or nodejs specific features. If they do, the library might work in one platform (e.g browser) but not the other.

"Node.js" is a server-side "JavaScript" platform. That means in a NodeJS app we replaces the typical server side languages like PHP, Ruby, etc.. with the JavaScript. When it comes to frontened we have been using Javascript and its libraries like JQuery for a very long time to add behavior to our apps. But after the recent boom of SPA(Single Page Applications) we can see lots of frameworks like Angular, Ember built on JavaScript to make SPA easier.
NPM is a package manager for JavaScript which itself uses Node to perform its operations. Using NPM we can bring many JavaScript packages (that includes all the client side JS libraries) to our project. But that does not mean your's is Nodejs app if you are using NPM to install AngularJs for your ASP.net application. It is like we need Ruby gems to install SASS preprocessor.
That's the beauty of a pure JavaScript(NodeJS) app. We can use the testing framework in both ends. Moreover that a developer can avoid mental switching between different syntax of the two languages, and even we can reuse some code/logic in both server and client side.

npm is a package manager for javascript. Using npm to import and manage packages for your application does not make it a Node.js app.
There is no such "Node.js apps". Applications refer to the front-end/client side.
You can choose Node.js or whatever on your back-end/server side, independently from your front-end.
I hope I have clarified a bit :-)

How to deploy a React + NodeJS Express application to AWS?

I have a React + Webpack/Babel + Node/Express application and I want to deploy it on AWS.
Would I have to deploy React and Node/Express separately? Or could they be deployed together at once?

1. If you have two distinct projects
e.g. a React single-page app and a Node/Express API.
a. You can deploy both separately
the frontend (the React app) on S3 and CloudFront (tutorial)
the backend (the Node API) on Elastic Beanstalk (recommended) or EC2
Another option is to deploy both parts together at once on Elastic Beanstalk or EC2. However, you'll miss out on the benefits of hosting on S3 and CloudFront, i.e. faster delivery for your users and cheaper costs. In my opinion, it's also more convenient and less prone to unexpected errors to update and deploy separately the client-side and the server-side of a web application.
Another benefit of deploying separately: For organizations with different teams for the frontend and backend, it's easier for each team to be able to deploy their side of the application on their own without depending on the other team.
b. Why S3 + CloudFront instead of S3 alone?
all the benefits of using a CDN
your own domain name and a free SSL certificate in 1-click
redirection on 4xx errors (necessary if your app uses a HTML5 History-based router)
the caching system
http2 and http to https redirection
c. How to handle CORS?
You can use different subdomains, e.g.
api.domain.com for the Node/Express API
app.domain.com for the React app
Then enable CORS in the API:
app.get('/api', cors({ origin: 'https://app.domain.com' }), ...)
2. If you have a single project
e.g. a Node app including some React views.
You have to deploy the whole app on Elastic Beanstalk or EC2.
Note: If you have a single project including two sub-projects (i.e. a folder for the React app and another one for the Node API), and if both sub-projects still work when they are separated, then you can deploy the sub-projects separately (see first part of the answer).
3. In both cases
Run your Webpack build before deploying the React part. You can do it manually (before deploying on AWS) or automatically (in your CI/CD system). If you bootstrapped your app with create-react-app (CRA), just run yarn build or npm run build at the root of the project and upload the content of the "build" folder to your S3 bucket.
4. Tools
Official AWS S3 CLI - Manage S3 buckets and objects using high-level aws s3 commands.
Official AWS Elastic Beanstalk CLI - Manage and deploy your backend using eb commands.
S3-deploy - CLI utility for deploying files to S3.
5. If not restricted to AWS
I answered a related question not restricted to AWS.

Basic Concepts
To deploy your app hassle free, you need to learn about three concepts: Microservices, containers, and process managers. I will discuss them with a bit more details and few links to get you started:
Microservices
Microservices is an architecture that allows you to divide your app into smaller services. This has multiple benefits:
1- The services are easily testable.
2- The services are replaceable.
3- The services can scale separately.
Containerization
Almost every useful app has at least dozens of dependencies. You can install dependencies on the target machines, but most certainly you'll face few challenges. Programs like Docker allow you to create a container for your app and deploy that container on the cloud. (Regardless of the cloud provider) Learn more...
Process Managers
Process managers ensure that your app is running smoothly and all parts are healthy. If your app crashes, it can easily restart the app.
1. Deploying a serverless NodeJS / React Application
Note: This approach does not work if you are doing server-rendering with ReactJS. Go to the next option.
You can simply build your app and deploy it to a static S3 website. This option works if you use microservices architecture to separate your API from your react app.
Creating a static website in S3 is really simple:
Create a bucket in S3 with the exact name of the website. Example: blog.stackoverflow.com.
Enable static hosting
Create an A record in Route 53 and connect it to the bucket you created.
For more information check AWS handy documentation.
2. Deploying a NodeJS application into EC2
You can launch different EC2 instances for every microservice. (API, React app, etc.) You need to use a process manager such as PM2 to ensure your app is running smoothly.
Continuous Delivery (Automating deployment)
To create an automatic deployment, I prefer to use Terraform in combination with Ansible. Terraform is very declarative. You describe how the cloud infrastructure should look like and Terraform build it for you.
Ansible, on the other hand, is very procedural and is perfect for provisioning a new server.
Error handling and reporting: Sentry
Ideally, you should have unit tests to prevent shipping buggy code to the production. (Use Jest with supertest, Enzyme for shallow rendering). But the world is imperfect, and it is good to receive any potential bugs that happen on the client. Enter Sentry

Both react and node code can be combined and deployed at once
you can more information here:
How to deploy reactjs and node typescript on elastic beanstalk using eb cli

Initialization in node.js || How to handle initial configuration in node.js

I recently transited from Java to JavaScript specifically MEAN Stack Development. I want to make API in node.js such that it initializes all configuration upon deployment like init method in Servlets.
If there is any other standardized way to accomplish this task kindly guide me.

You have to go with Loopback is a highly-extensible, open-source Node.js API framework.
Features
Quickly create dynamic end-to-end REST APIs.
Connect devices and browsers to data and services.
Use Android, iOS, and AngularJS SDKs to easily create client apps.
Add-on components for push, file management, 3rd-party login, and geolocation.
Use StrongLoop Arc to visually edit, deploy, and monitor LoopBack apps.
StrongLoop API Gateway acts an intermediary between API consumers (clients) and API providers to externalize, secure, and manage
APIs.
Runs on-premises or in the cloud
How to install - To install this, simply run the following given command.
$ npm install -g strongloop
Hope this will help to resolve your query !!

You could look at Swagger which provides many tools for configuring, representing and validating a RESTful API.
There is a swagger-node module which, after defining your JSON API schema, can automatically configure your API for you.