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Uncontrolled Functional Component with RadioButton, ListBox, DropdownList and Checkbox

 Uncontrolled Functional Component with RadioButton, ListBox, DropdownList and Checkbox:



Example of RadioButton:


import { useRef,useState } from "react";
function RadioExampleNew()
{
    const course1 =useRef()
    const course2 =useRef()
    const course3 =useRef()
    const[res,setRes] = useState(undefined)
    function displayCourse(e)
    {
        if(course1.current.checked)
        {
            setRes(course1.current.value)
        }
        else  if(course2.current.checked)
            {
                setRes(course2.current.value)
            }
            else
            {
                setRes(course3.current.value)
            }
        e.preventDefault()
    }
    return(<div>
        <form>
            <p>Select Course</p>
            <input type="radio" name="course" value="MERN STACK" ref={course1} />MERN
            <br/>
            <input type="radio" name="course" value="MEAN STACK" ref={course2} />MEAN
            <br/>
            <input type="radio" name="course" value="JAVA FULL STACK" ref={course3} />
JAVA FULL STACK
            <br/>
            <input type="submit" value="submit" onClick={displayCourse} />
        </form>
        {res}
    </div>)
}
export default RadioExampleNew;

Example of Listbox:
import { useRef } from "react";

function DropdownList()
{
    const sel = useRef([])
    function fun(e)
    {
        let course1="";
        console.log(sel.current.selectedOptions)
        const selectedOptions = Array.from(sel.current.selectedOptions,
            option => option.value);
        alert(selectedOptions)
       e.preventDefault()
    }
    return(<div>
        <form onSubmit={fun}>
            <select  ref={sel} multiple>
                <option value="C">C</option>
                <option value="CPP">CPP</option>
                <option value="DS">DS</option>
                <option value="REACT">REACT</option>
            </select>
            <br/>
            <input type="submit" value="Submit" />
        </form>
    </div>)
}
export default DropdownList;

Another Example of Listbox:

import { useRef,useState } from "react";
function Listboxnew()
{
    const course=useRef([])
    const[res,setRes] = useState(undefined)
    const arr = ["C","C++","DS","JAVA","PHP","PYTHON","Android","iOS"]
   
    function displayCourse(e)
    {
        const selectedOptions = Array.from(course.current.selectedOptions,
option => option.value);
        setRes(selectedOptions.join(','))
        e.preventDefault()
    }
   
    return(<div>
        <form>
            <p>Select Course</p>
            <select name="course" ref={course}  multiple>
             {arr.map(item=>(<option value={item}>{item}</option>))}
            </select>
            <br/>
            <input type="submit" value="submit" onClick={displayCourse} />
        </form>
        {res && <div>Result is {res}</div>}
    </div>)
}
export default Listboxnew;

Example of checkbox:

import { useRef } from "react";

function CheckboxExample()
{
   const chk1 = useRef()
   const chk2 = useRef()
   const chk3 = useRef()
   function selectCourse(e)
   {
    let course1="",course2="",course3=""
    if(chk1.current.checked){
        course1=chk1.current.value
    }
    else
    {
        course1=' '
    }
    if(chk2.current.checked){
        course2=chk2.current.value
    }
    else
    {
        course2=' '
    }
    if(chk3.current.checked){
        course3=chk3.current.value
    }
    else
    {
        course3=' '
    }
    alert("selected course is "+(course1+ " " +course2+ " " +course3))
    e.preventDefault()
   }
    return (<div>
       <form onSubmit={selectCourse}>
        <input type="checkbox" value="C" ref={chk1}/>C <br/>
        <input type="checkbox" value="CPP" ref={chk2} />CPP <br/>
        <input type="checkbox" value="DS" ref={chk3} />DS <br/>
        <input type="submit" name="btnsubmit" value="Select Course" />
       </form>
    </div>)
}

export default CheckboxExample;

Optimize code of Checkbox:

import { useRef } from "react";

function CheckboxExample()
{
   const chk = useRef([])
 
   function selectCourse(e)
   {
 
    let course1="";

 
    for (let index in chk.current) {
      if (chk.current[index].checked) {
        course1 += chk.current[index].value + " ";
      }
    }

    alert("Selected course(s): " + course1);
    e.preventDefault();
   }
    return (<div>
       <form onSubmit={selectCourse}>
        <input type="checkbox" value="C"  ref={(el) => (chk.current[0] = el)}/>C <br/>
        <input type="checkbox" value="CPP"  ref={(el) => (chk.current[1] = el)} />CPP <br/>
        <input type="checkbox" value="DS"  ref={(el) => (chk.current[2] = el)} />DS <br/>
        <input type="submit" name="btnsubmit" value="Select Course" />
       </form>
    </div>)
}

export default CheckboxExample;

Code of DropdownList:

import { useRef } from "react";

function DropdownList()
{
    const sel = useRef()
    function fun(e)
    {
       alert(sel.current.value)
       e.preventDefault()
    }
    return(<div>
        <form onSubmit={fun}>
            <select  ref={sel}>
                <option value="C">C</option>
                <option value="CPP">CPP</option>
                <option value="DS">DS</option>
                <option value="REACT">REACT</option>
            </select>
            <br/>
            <input type="submit" value="Submit" />
        </form>
    </div>)
}
export default DropdownList;
Create Dynamic Dropdown List:

import { useRef } from "react";

function DropdownList()
{
    const sel = useRef([])
    const items = ['C', 'C++', 'DS','JAVA','PHP','iOS','Android'];
    const startYear = 1990;
    const endYear = 2050;
    const years = [];
 
    for (let year = startYear; year <= endYear; year++) {
      years.push(year);
    }
    function fun(e)
    {
        let course1="";
        console.log(sel.current.selectedOptions)
        const selectedOptions = Array.from(sel.current.selectedOptions,
            option => option.value);
        alert(selectedOptions)
        e.preventDefault()
    }
    return(<div>
        <form onSubmit={fun}>

            <select  ref={sel} multiple>
            {items.map((item, index) => (
                      <option key={index}>{item}</option>
            ))}
            </select>
            <br/>
            <select>
            {years.map((item, index) => (
                      <option key={index}>{item}</option>
            ))}
            </select>
            <br/>
            <input type="submit" value="Submit" />
        </form>
    </div>)
}
export default DropdownList;

Radio button example to Change Background-color:

import { useRef, useState } from "react"

function ChangebgColor()
{
    const rb = useRef()
    const rb1 = useRef()
    const rb2 = useRef()
    const [c,setC] = useState()
    function changeColor()
    {
        if(rb.current.checked)
             setC(rb.current.value)
        else if(rb1.current.checked)
            setC(rb1.current.value)
        else
            setC(rb2.current.value)

    }
    return(<div style={{'backgroundColor':c,width:"1500px",height:"800px"}}>
        <input type="radio" name="color" ref={rb} value="Red" onClick={changeColor} />RED
        <br/>
        <input type="radio"  name="color" ref={rb1} value="Green" onClick={changeColor} />Green
        <br />
        <input type="radio"  name="color" ref={rb2} value="Blue" onClick={changeColor} />Blue
        </div>)
}
export default ChangebgColor;
Example of Addition with Multiple Textfield:
import { useRef, useState } from "react"

function Addition()
{
    const txt1ref = useRef()  //hook
    const txt2ref = useRef()  //hook
   
    const[res,setRes]= useState(undefined) //state
    function calc(ope,e)
    {
       
        let num1 = txt1ref.current.value
        let num2 = txt2ref.current.value
        var num3;
        switch(ope)
        {
            case '+':
                num3 = parseInt(num1)+parseInt(num2)
                break
            case '-':
                num3 = parseInt(num1)-parseInt(num2)
                break
            case '*':
                num3 = parseInt(num1)*parseInt(num2)
                break
            case '/':
                num3 = parseInt(num1)/parseInt(num2)
                break
            default:
               break;        
            }
       
        setRes(`result is ${num3}`)
        e.preventDefault()
    }
   
   return(<div>
    <form>
        <input type="text" ref={txt1ref} placeholder="Enter First Number" /> <br/>
        <input type="text" ref={txt2ref} placeholder="Enter Second Number" /> <br/>
        <input type="submit" onClick={(e)=>calc("+",e)} value="Addition" />
        <input type="submit"  onClick={(e)=>calc("-",e)} value="Substraction" />
        <input type="submit"  onClick={(e)=>calc("*",e)} value="Multiplication" />
        <input type="submit"  onClick={(e)=>calc("/",e)} value="Division" />


    </form>
      {res}
   </div>)
}
export default Addition;


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