ref for functional component code example

Example 1: 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 2: refs react js

class Lesson9Refs extends Component {

    onAddProduct = () => {
        alert(this.refs.productname.value);
    }
    
    
    return (

            <div>

                <div className="container">
                    <div class="card mt-10">
                        <div class="card-header">
                            Featured
                        </div>
                        <div class="card-body">
                          
                            <label> Product Name: </label>
                            <input type='text' className="form-control" ref="productname" />  

                            <button type="submit" className="btn btn-primary" onClick={ this.onAddProduct } >
                                Add Product
                            </button>

                        </div>
                    </div>
                    <div className="row mt-10">
                        { elements }
                    </div>
                </div>
            </div>
        );

    }
}

export default Lesson9Refs;

Example 3: ref in functional components

function MyFunctionComponent() {  return <input />;
}

class Parent extends React.Component {
  constructor(props) {
    super(props);
    this.textInput = React.createRef();  }
  render() {
    // This will *not* work!
    return (
      <MyFunctionComponent ref={this.textInput} />    );
  }
}

Example 4: ref in functional components

function CustomTextInput(props) {
  // textInput must be declared here so the ref can refer to it  const textInput = useRef(null);  
  function handleClick() {
    textInput.current.focus();  }

  return (
    <div>
      <input
        type="text"
        ref={textInput} />      <input
        type="button"
        value="Focus the text input"
        onClick={handleClick}
      />
    </div>
  );
}