React js

                                   react

useState is type of reactjs hooks

The React useState Hook allows us to track state in a function component.

State generally refers to data or properties that need to be tracking in an application.

import React from "react";

import { useState } from "react";

function Hh (){

   let [counter , setCounter]= useState(10)

    // let counter = 5

    const addValue = () =>{

        // counter = counter + 1;

        setCounter(counter + 1);

    }

    const removeValue  =()=>{

        counter=counter - 1;

        setCounter(counter);

    }

        return(

            <>

                <h1>Chai or react</h1>

                <h2>counter value : {counter}</h2>

                <button onClick={addValue}>Add value</button>

                <br/>

                <button onClick={removeValue}>Remove value</button>

            </>

        )

}

export default Hh;

usememo

import React,{useMemo, useState} from "react";

function Hp(){

    const [count,setCount]=useState(0)

    const [item,setItem]=useState(10)

    let multiCountMemo=useMemo(function multiCount(){

        return count*5;

    },[count])

   

    return(

        <>

            <h1>harshvardhan </h1>

            <h2>count : {count}</h2>

            <h2>Item : {item}</h2>

            <br/>

            {multiCountMemo}

            <br/>

            <button onClick={()=>setCount(count+1)}>Update count</button>

            <button onClick={()=>setItem(count*10)}>Update Item</button>

        </>

    );

}

export default Hp;

useeffect

import React, { useState, useEffect } from "react";

const UseEffect = () => {

  const [count, setCount] = useState(0);

  const countUpdate = (val) => {

    if (val === "inc") return setCount(count + 1);

    if (val === "dec") return setCount(count - 1);

  };

  useEffect(() => {

    document.title = count;

  }, [count]);

  return (

    <>

      <Wrapper>

        <div className="container">

          <button onClick={() => countUpdate("inc")}>

          </button>

          <h1>{count}</h1>

          <button onClick={() => countUpdate("dec")}>

            <FaMinus className="icon minus_icon" />

          </button>

        </div>

      </Wrapper>

    </>

  );

};

export default UseEffect;

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