How to use React.useRef() in class component?

Question

I need this code to be implemented in class component. It is in order to use a upload progress in my class component with react-toastify

function Example(){
  const toastId = React.useRef(null);
  function handleUpload(){
    axios.request({
      method: "post", 
      url: "/foobar", 
      data: myData, 
      onUploadProgress: p => {
        const progress = p.loaded / p.total;
        if(toastId.current === null){
            toastId = toast('Upload in Progress', {
            progress: progress
          });
        } else {
          toast.update(toastId.current, {
            progress: progress
          })
        }
      }
    }).then(data => {
      
      toast.done(toastId.current);
    })
  }
  return (
    <div>
      <button onClick={handleUpload}>Upload something</button>
    </div>
  )
}

How can i do that?

score 93 · Answer 1 · edited Aug 24 '22 at 15:32

93

useRef() is among react hooks which are meant to be used in Functional components. But if you want to create a reference in a class-based component, you can do it from the class constructor like the code below:

  constructor(props) {
    super(props);
    this.myRef = React.createRef();
  }

Check React.createRef().

edited Aug 24 '22 at 15:32

Gibron

1,350
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answered Jun 21 '20 at 13:21

Mwibutsa Floribert

1,824
14
21

score 5 · Answer 2 · answered Mar 11 '22 at 15:29

5

Assign your value in constructor i.e bind with this.

createRef !== useRef, useRef is used to preserve the value across re-renders and for that in class component you need to bind it with this not createRef

answered Mar 11 '22 at 15:29

Gargi Goyal

109
1
4

6

you should add a code example – Facundo Colombier May 31 '22 at 19:51
1

As @FacundoColombier said, the answer should contain a code example. – Nikitas IO Jan 11 '23 at 22:07

score 0 · Answer 3 · answered Jun 11 '23 at 00:01

How to use React.useRef() in class extends component:

import { Component, createRef } from "react";

export default class App extends Component{
 constructor(props){
    super(props);
   
    this.myP = createRef();
    window.addEventListener("load", ()=>this.prompt());
 }
 prompt(){
     this.myP.current.innerText = 'Hello World!'
 }
 render(){
    return(
        <>
          <p ref={this.myP} />        
        </>
    );
 }
}

How to use React.useRef() in class component?

3 Answers3

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