This content originally appeared on DEV Community and was authored by mohandass
1. What is React j.s
React is a free and open source JavaScript library. It's used for Building user interfaces(UIs) specifically for single-page Applications(SPA). Created by Facebook(now meta) in 2013,it's allows Developers create large web application that can change data without Reloading the page.
React helps developers create:
- Websites
- Single Page Applications (SPA)
- Dashboards
- E-commerce apps
- Social media apps
- Mobile apps (with React Native)
Why React was Created
- React was created to solve problems developers faced while building larger and dynamic web applications.
Before React, developers updated HTML manually using JavaScript.
Example:
document.getElementById("title").innerHTML = "welcome";
When the application become larger:
- Code became messy
- Updating UI became difficult
- Performance issues happened
React solving this by introducing :
Components,Virtual DOM,State management,Reusable UI
2. What is the different between library and Framework ?
- The primary difference between a library and a framework is Inversion of Control(IOC) in short, When you use a library, your are the in charge; When you use a framework, the framework is in charge.
Use a library when:
- You need flexibility
- Small project
- Specific feature only
- Want custom architecture
Use a framework when:
- Building large applications
- Need standard structure
- Team collaboration
- Faster large-scale development
Simple Concept
Library = Helper-(It helps your code)
Framework = Foundation-(Your app runs inside it)
3. What is Build Tool
- A build tool is a software utility that automates the process of converting source code.which typically includes JSX, modern JavaScript (ES6+), and CSS—into a optimized, production-ready format that web browsers can understand
Why Build Tools Are Needed
Modern web applications use:
- Multiple files
- React components
- TypeScript
- SCSS
- Images
- APIs
- Modules
Browsers cannot directly understand everything.
For example:
-Browsers do not understand JSX directly
-Browsers do not understand TypeScript directly
Build tools convert them into normal JavaScript, HTML, and CSS.
Common Examples by Language
Java - Apache Maven, Gradle
JavaScript - npm,webpack,vite
C/C++ - Make, CMake
Python - Poetry, pip
4. What is vite
- Vite (pronounced “veet”) is a modern frontend build tool used to create fast web applications.It offers instant server startup and lightning-fast Hot Module Replacement (HMR), making it a popular replacement for tools like Create React App.
Why Vite Was Created
Older build tools like:
Webpack
became slow for large applications.
Problems:
-Slow startup
-Slow rebuilds
-Slow hot reload
Vite was created to solve these speed problems.
Vite helps developers:
-Start projects quickly
-Run development servers
-Bundle files
-Optimize applications
This content originally appeared on DEV Community and was authored by mohandass
mohandass | Sciencx (2026-05-13T16:50:36+00:00) What is React.js. Retrieved from https://www.scien.cx/2026/05/13/what-is-react-js-2/
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