Introduction to Node js

01 What is Node.js?

Node.js is an open-source platform – It allows JavaScript to run on a server.
It is free to use – Anyone can use it without paying.
Works on multiple operating systems – Supports Windows, Linux, macOS, and more.
Uses JavaScript on the server – Helps in building fast and scalable web applications.

Imagine you want to cook food.
A kitchen is needed because it provides space and tools for cooking.
The kitchen is not the food, but it helps you prepare it.
Similarly, Node.js is not a programming language, but it provides an environment to run JavaScript outside the browser.

Express.js is a web framework for Node.js – It makes building web and mobile applications easier.
It is minimal and flexible – Provides essential tools without unnecessary complexity.
Helps in running Node.js as a server – Makes handling requests and responses simpler.
Without Express.js, using Node.js directly can be difficult – Express provides ready-made features that save time and effort.

Imagine you want to travel a long distance.
You can walk, but it will be slow and tiring.
Instead, you take a bus, which makes the journey faster and more comfortable.
Similarly, Node.js alone is like walking, while Express.js is like the bus that makes server-side development easier and faster.

MongoDB is a document-based database – It stores data in a flexible and scalable way.
Uses collections and documents – A collection holds multiple documents (similar to tables in SQL).
Schema-less database – You can store any type of data inside any collection.
Powerful querying and indexing – Helps in retrieving data efficiently.

Suppose you want to store users and their posts in a database.
You will create two collections:
- Users Collection → Stores user details.
- Posts Collection → Stores posts written by users.
Each user and post is saved as a separate document inside its respective collection.

MongoDB doesn’t enforce a strict structure – It allows storing any data inside any collection.
Example: You can accidentally store product data inside the Users Collection, which can cause issues.

Mongoose is a library that helps define a schema for MongoDB.
It tells MongoDB:
- “Hey! A user should only have name, email, and password fields!”
- This ensures only valid data is stored in the correct collection.

Mongoose is an ODM (Object Document Mapper) for MongoDB – It helps in managing data easily.
What is ODM? – ODM maps objects in code to documents in a database, just like how ORM (Object Relational Mapper) maps objects to tables in SQL databases.
Why do we need Mongoose? – MongoDB is schema-less, meaning it allows storing any data in any collection.
Mongoose helps by defining a schema – It ensures that each collection stores only the correct type of data.

Imagine you are running a school and have a Student Register.
You want each student’s entry to have only a Name, Age, and Class.
Without rules, someone might enter extra information like phone number or address, making records messy.
Mongoose works like a strict register – It makes sure only Name, Age, and Class are recorded in the Student Register.

Creates a schema – Defines which fields a document should have.
Ensures data consistency – Prevents incorrect or unnecessary data from being stored.

Makes querying easy – Provides built-in functions to interact with MongoDB.