this.refs in react code example

Example 1: react focus

const FocusDemo = () => {

    const [inputRef, setInputFocus] = useFocus()

    return (
        <> 
            <button onClick={setInputFocus} >
               FOCUS
            </button>
            <input ref={inputRef} />
        </>
    )

}

const useFocus = () => {
    const htmlElRef = useRef(null)
    const setFocus = () => {htmlElRef.current &&  htmlElRef.current.focus()}

    return [ htmlElRef, setFocus ] 
}

Example 2: react.createref()

class CustomTextInput extends React.Component {
  constructor(props) {
    super(props);
    // create a ref to store the textInput DOM element
    this.textInput = React.createRef();    this.focusTextInput = this.focusTextInput.bind(this);
  }

  focusTextInput() {
    // Explicitly focus the text input using the raw DOM API
    // Note: we're accessing "current" to get the DOM node
    this.textInput.current.focus();  }

  render() {
    // tell React that we want to associate the <input> ref
    // with the `textInput` that we created in the constructor
    return (
      <div>
        <input
          type="text"
          ref={this.textInput} />        <input
          type="button"
          value="Focus the text input"
          onClick={this.focusTextInput}
        />
      </div>
    );
  }
}

Example 3: use ref in component reactjs

function CustomTextInput(props) {
  return (
    <div>
      <input ref={props.inputRef} />    </div>
  );
}

class Parent extends React.Component {
  render() {
    return (
      <CustomTextInput
        inputRef={el => this.inputElement = el}      />
    );
  }
}

Example 4: use ref in component reactjs

class CustomTextInput extends React.Component {
  constructor(props) {
    super(props);
    // Crée une référence pour stocker l’élément DOM textInput
    this.textInput = React.createRef();    this.focusTextInput = this.focusTextInput.bind(this);
  }

  focusTextInput() {
    // Donne explicitement le focus au champ texte en utilisant l’API DOM native.
    // Remarque : nous utilisons `current` pour cibler le nœud DOM
    this.textInput.current.focus();  }

  render() {
    // Dit à React qu’on veut associer la ref `textInput` créée
    // dans le constructeur avec le `<input>`.
    return (
      <div>
        <input
          type="text"
          ref={this.textInput} />        <input
          type="button"
          value="Donner le focus au champ texte"
          onClick={this.focusTextInput}
        />
      </div>
    );
  }
}