refs and the dom 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: cre&atRefs react js

const node = this.myRef.current;