import React, { PureComponent } from 'react';

class MyComponent extends PureComponent {
  constructor(props) {
    super(props);
    this.myRef = React.createRef();
  }

  componentDidMount() {
    console.log(this.myRef);
  }

  render() {
    return (
      <div className="test" ref={this.myRef} />
    );
  }
}

{current: null}