React Js Notes

Initial Setup

1. npm create vite@latest - to create react app
2. cd project_folder
3. npm install - to install node modules
4. npm run dev - to run react app

Tailwind css

1. npm install -D tailwindcss postcss autoprefixer - to install tailwind

2. npx tailwindcss init -p - to create tailwind files

3. make changes in content:[] of tailwind.config.js -

    content: [  
    "./index.html",  
    "./src/**/*.{js,ts,jsx,tsx}",  
   ],
   

4. inject tailwind in index.css -

   @tailwind base;  
   @tailwind components;  
   @tailwind utilities;`  
   

Deploy Vite React App on Netlify

1. npm run build
2. Drag and Drop dist folder on netlify

Learnings

Lec2 - Creating Components

• Creating Components dir in src
• Creating componentname.jsx file in Components dir
• rafce - Snippet for boiler plate for componentname.jsx and app.jsx

Lec3 - Components Reusability

• Creating array and applying map method on that array and returning all the elements of array in html with dynamic values of all elements to display it

•  arr.map(()=>(html code))  
  

Lec4 - Conditional Rendering

• Card.jsx is used

• eg:

  <!-- here conditional rendering is used for button color -->  
  <button
    className={`px-4 py-1
    ${elem.instock?'bg-blue-600':'bg-red-600'}
     rounded text-xs text-zinc-100 mt-3`}>   
  {elem.instock ? "In Stock" : "Out of Stock"} <!-- this is conditional rendering -->  
  </button>  
  

Handling events

• Cardz.jsx is used
• onClick={handleClickDownload} - on button

Lec5,6,7 - useState hook

• const [val,setVal] = useState(initial_value)  
  

• <button
     onClick={()=>setVal(()=>val.filter((item)=>item%2!==0))}
     className='px-2 py-1 text-white rounded-full bg-blue-500'>
     click
  </button>  
  

•    <button
     onClick={()=>setVal({...val,isBanned:!val.isBanned})}
     className={`px-3 py-1
       ${val.isBanned?'bg-blue-600':'bg-red-600'}
       text-xs rounded-full text-white`}>
     Change
  </button>  
  

Lec8 - Passing data via props from parent to child

Basic example :

• App.jsx (parent) -

  <Card text="Know More" color="bg-blue-600"/>
  <Card text="Download" color="bg-red-600"/>
  

• Card.jsx (child) -

    const Card = ({text,color}) => {  
    return (  
    <button className={`px-3 py-1 ${color} text-zinc-100 text-xs m-2 rounded`}>{text}</button>  
    )  
    }  
  

Lec9 - Exercise of states and component

Extra : style.module.css also import it for using

Lec10 - Form Handling

• To stop reloading of page after form submission we use e.preventDefault()
  we have 3 methods :
• useRef => is tareeke mein hum har input ko select kar lete hai and unki value tab nikalte hai jab form submit hota hai
• controlled components => updating real time data using state
• react hook form (mostly used) npm install react-hook-form

Lec11 - Exercise of form Handling

Lec12 - Routing

• npm i react-router-dom - install react-router-dom

• import {BrowserRouter} from 'react-router-dom' - import in main.jsx for using ...

    ReactDOM.createRoot(document.getElementById('root')).render(  
      <React.StrictMode>  
        <BrowserRouter>  
          <App />  
        </BrowserRouter>  
      </React.StrictMode>,  
    )
  

• Make a folder name utils in src
  inside of utils make Routing.jsx

• import all the pages and routes,route in Routing.jsx

    import {Route,Routes} from 'react-router-dom'  
    import Home from "../Components/Home"  
    import About from "../Components/About"  
    import User from "../Components/User"
  

• using routes and route in Routing.jsx

    <Routes>  
      <Route path="/" element={<Home/>} />  
      <Route path="/user" element={<User/>} />  
      <Route path="/about" element={<About/>} />  
    </Routes>
  

• import {Link,NavLink} from 'react-router-dom' - import in Nav.jsx for using it

• <Link to="/user">User</Link> - using link in Nav.jsx

• instead of <Link></Link>, use <NavLink></NavLink>
<NavLink></NavLink> takes a function(callback) for styling purpose

• In App.jsx,
  import - import Nav from "./Components/Nav" and import Routing from "./utils/Routing"
  use as - <Nav/> <Routing path="/nav" element={<Nav/>}/>

• Dynamic styling on NavLink

1. Dynamic style inside {} open brackets and returing span tag
2. Dynamic styling using style
3. Dynamic styling using className

Lec13 - Dynamic/child routing

• Create UserDetail.jsx in Components

• import { useNavigate, useParams } from 'react-router-dom' - import useParams and useNavigate in UserDetail.jsx

• Use it in UserDetail.jsx

    const {name}=useParams() <!-- for dynamic routing-->  
    const navigate=useNavigate()  <!-- for navigating using button  -->  
    const GoBackHandler=()=>{  
    navigate("/user")  
    }
  

• Use it in UserDetail.jsx

    <button
       onClick={GoBackHandler}
       className='mt-5 text-white px-3 py-2 bg-red-300'>
       Go back
    </button>  
  

• In Routing.jsx for dynamic routing

    <Route path="/user/:name" element={<UserDetail/>} />   
  

• In User.jsx, Add Links for directing to particular user dynamically

• For not keeping UserDetail as separate page and display it on the same page,

• import - import {Link,Outlet} from 'react-router-dom'

• Use - <Outlet/> which acts as a placeholder in User.jsx itself
  Also do some changes in Routing.jsx i.e. make nested route User->UserDetail

    <Route path="/user" element={<User/>} >
        <Route path="/user/:name" element={<UserDetail/>} />
    </Route>
  

• Flow :
  main->BrowserRouter->App(tag)
  App->Nav,Routing(routing)
  Routing->Home,User,UserDetail,About(routing)
  User->UserDetail(dynamic routing)

Lec14 - Api Integration

• Show.jsx

• npm i axios

• import axios from 'axios' - import axios

• useState and then make function to get data through api

• axios gives us implementation of ajax(async js and xml) - fetch/axios

• Use of axios :

    axios.get("api-link")  
    .then((e)=>{  
    setState(e.data)  
    })  
    .catch(e=>console.log(e));  
  

Life cycle of components -
Component Mount (creation)
Component Update (changes in same page)
Component Unmount (deletion)

Lec15 - useEffect

• Services.jsx, Show.jsx
  to avoid clicking and do direct rendering of components we use useEffect

• import useEffect -

  import { useEffect } from 'react' 
  
  useEffect(() => {  
    console.log("Service component is created!")
  return () => {  
    console.log("Service component is deleted!")  
  }
  }, [second])  
  

• second - on clicking 2nd button service page gets re-render where as on clicking 1st button service page do not gets re-render
  if u pass empty array in 2nd argument then rerendering of that page stops even on state change

• instead of importing axios in every file import it in utils/axios.jsx and use it's reference in every page wherever required

• utils/axios.jsx -

  import axios from "axios";  
    const instance=axios.create({  
   baseURL:"https://fakestoreapi.com/",  
   })  
   export default instance  
  

• Use this reference in other pages for importing axios and then
  import axios from '../utils/axios'

• Use it as -

    const api="/products"; 
    axios.get(api).then(callback).catch(callback)  
  

Lec16 - Context Api

1. Create Context dir in src and Context.jsx inside Context dir
2. We wrapped the browerRouter and app by Context
3. We created context inside Context.jsx file

Context.jsx -

import React, { createContext, useState } from 'react'

export const UserContext = createContext();
const Context = (props) => {
const [users,setUsers]=useState([
    { id:0,username:"John Doe",city:"USA",},
    { id:1,username:"Jenny Doe",city:"Colambia",},
    { id:2,username:"Joseph Doe",city:"Korea",},
]);

  return (
    <UserContext.Provider value={{users,setUsers}}>
      {props.children}
    </UserContext.Provider>
  );
}

export default Context