Light's Blog

 1. What is MongoDB? MongoDB is a no SQL database, which stores Documents in Collections instead of Records in Tables as in SQL It is used to store application data Stored data doesn't enforce a specific data schema or any relations MongoDB can also be easily connected to Node and Express, but we do not connect it directly to our front end (React) MongoDB is a powerful database and it can be easily integrated into a node express environment 2. SQL vs NoSQL NoSQL(e.g MongoDB) do not enforce a strict data schema(collections can contain documents with different schemas),  have less focus on relations, works with independent documents SQL(e.g MySQL) enforce a strict data schema(define the tables and the corresponding records, normally don't deviate from that structure ), relations are a core feature the records are related 3. Connecting React to a Database? Connecting react to the database is a bad idea It is a highly insecure approach, secure authentication is not really possible

 1. What is Node.js? Like Browser is one host environment of that Javascript of frontend, Node.js is a host environment for Javascript of backend Chrome's Javascript engines V8  has all been cloned and is now maintained as a standalone project working without a browser and enriched with some extra APIs that is basically Node.js, it allows us to run Javascript outside of the browser Compare to V8, Node.js dropped some APIs(e.g. DOM API), and added some APIs(e.g. Filesystem) 2. A Simple Node.js Code Node.js code are just normal javascript code with extra node  api In Node.js runtime environment, there are a few globally function (e.g., require) Between different Node.js module (javascript file), we can transfer object through require and export A simple Node.js Code: const fs = require("fs"); const userName = "Light"; fs.writeFile("./user-data.txt", "Name: " + userName, (error) => { if (error) { console.log(error); return; }

 1. What is React? It's a Javascript library for building user interfaces that are shown in the browser It's a browser side Javascript library running in browser It started a huge ecosystem with other third-party packages forming a framwork We use it to build the frontend of web applications React does not run on a server, React does not communicate with databases React build highly reactive modern user interfaces and do so by following a declarative approach(you define the results, not the steps that lead to the result) React using components which are UI building blocks we can define, then we compose our user interface from these components Every component also define what it should render, under which circumstance 2. React Component React component can be one of two things, it can be a Javascript function which returns jsx or it can be a Javascript class that has a render method Custom components can be used as jsx( JavaScript XML ) as well,  they should start with a capital