getting ref values in react

ref.js

const AddTodo = ({
  onAddClick
}) => {
  let input;

  return (
    <div>
      <input ref={node => {
        input = node;
      }} />
      <button onClick={() => {
        onAddClick(input.value);
        input.value = '';
      }}>
        Add Todo
      </button>
    </div>
  );
};