रिएक्ट में क्यूआर कोड जेनरेटर कैसे बनाएं

 npx create-react-app qrcode-generator

 cd qrcode-generator npm start

 npm install qrcode.react

 // src/components/QrCode.js
import { useState } from "react" ; import { QRCodeCanvas } from "qrcode.react" ; const QrCode = () => {  const [url, setUrl] = useState( "" );  const downloadQRCode = ( e ) => {  e.preventDefault();  setUrl( "" ); };  const qrCodeEncoder = ( e ) => {  setUrl(e.target.value); };  const qrcode = (    < QRCodeCanvas
      id = "qrCode"
      value = {url}
      size = {300}
      bgColor = { "# 00ff00 "}      level = { " H "}  />
 );  return (    < div className = "qrcode__container" >
      < div > {qrcode} </ div >
      < div className = "input__group" >
        < form onSubmit = {downloadQRCode} >
          < label > Enter URL </ label >
          < input
            type = "text"
            value = {url}
            onChange = {qrCodeEncoder}
            placeholder = "https://hackernoon.com"
     />
          < button type = "submit" disabled = {!url} >
      Download QR code          </ button >
        </ form >
      </ div >
    </ div >
 ); }; export default QrCode;

 /* src/styles.css */
*, *:before, *:after { margin: 0 ;  padding : 0 ;  box-sizing : border-box; } :root { -- font - color : 230 35% 7% ; } body {  color : hsl ( var (--font-color)); } img {  max-width : 100% ;  display : block; } .section {  padding : 2em 0 ;  display : flex;  min-height : 100vh ;  align-items : center; } .container {  margin -inline: auto;  max-width : 75rem ;  width : 85% ; } .input__group {  display : flex;  margin-top : 2em ; } input {  width : 100% ;  padding : 1em 0.75em ;  border : 1px solid #444343 ;  border-radius : 3px ;  margin-bottom : 2em ;  margin-top : 0.75em ; } button {  border : unset;  background : hsl ( 231 , 77% , 90% );  padding : 1em 0.75em ;  color : hsl ( var (--font-color));  cursor : pointer;  text-transform : uppercase;  font-weight : bold; } @media screen and ( min-width : 768px ) {  .section {    padding : 0 ; }  input {    margin : 0 ; }  .qrcode__container {    display : flex;    align-items : center; }  .input__group {    margin-left : 3em ; }  input {    margin-bottom : 2em ;    margin-top : 0.75em ;    font-size : 1rem ; } }

 // src/App.js
import QrCode from "./components/QrCode" ; import "./styles.css" ; export default function App ( ) {  return (    < div className = "section container" >
      < QrCode />
    </ div >
 ); }

 // src/components/QrCode.js
import { useState, useRef } from "react" ; // other import
const QrCode = () => {  const [url, setUrl] = useState( "" );  const qrRef = useRef(); // include this: call the useRef function
 ...  const qrcode = (    < QRCodeCanvas
      id = "qrCode"
      value = {url}
      size = {300}
      bgColor = { "# 00ff00 "}      level = { " H "}  />
 );  return (    < div className = "qrcode__container" >
      < div ref = {qrRef} > {qrcode} </ div > {/* include this */}   {/* form input container */}    </ div >
 ); }; export default QrCode;

 // src/components/QrCode.js
// imports
const QrCode = () => {  // state
  // useRef
  const downloadQRCode = ( e ) => {  e.preventDefault();    let canvas = qrRef.current.querySelector( "canvas" );    let image = canvas.toDataURL( "image/png" );    let anchor = document .createElement( "a" );  anchor.href = image;  anchor.download = `qr-code.png` ;    document .body.appendChild(anchor);  anchor.click();    document .body.removeChild(anchor);  setUrl( "" ); }; ...  return (    < div className = "qrcode__container" >
      < div ref = {qrRef} > {qrcode} </ div >
   {/* form input container */}    </ div >
 ); }; export default QrCode;

 import { useState, useRef } from "react" ; import { QRCodeCanvas } from "qrcode.react" ; const QrCode = () => {  const [url, setUrl] = useState( "" );  const qrRef = useRef();  const downloadQRCode = ( e ) => { e.preventDefault();    let canvas = qrRef.current.querySelector( "canvas" );    let image = canvas.toDataURL( "image/png" );    let anchor = document .createElement( "a" ); anchor.href = image; anchor.download = `qr-code.png` ;    document .body.appendChild(anchor); anchor.click();    document .body.removeChild(anchor); setUrl( "" ); };  const qrCodeEncoder = ( e ) => { setUrl(e.target.value); };  const qrcode = (    < QRCodeCanvas
      id = "qrCode"
      value = {url}
      size = {300}
      bgColor = { "# 00ff00 "}      level = { " H "} />
 );  return (    < div className = "qrcode__container" >
      < div ref = {qrRef} > {qrcode} </ div >
      < div className = "input__group" >
        < form onSubmit = {downloadQRCode} >
          < label > Enter URL </ label >
          < input
            type = "text"
            value = {url}
            onChange = {qrCodeEncoder}
            placeholder = "https://hackernoon.com"
 />
          < button type = "submit" disabled = {!url} >
 Download QR code          </ button >
        </ form >
      </ div >
    </ div >
 ); }; export default QrCode;