How to use React forwardRef

Ref forwarding is a technique for automatically passing a ref through a component to one of its children. This is typically not necessary for most components in the application. However, it can be useful for some kinds of components, especially in reusable component libraries. The most common scenarios are described below.

import React, { createRef, forwardRef, ChangeEventHandler } from 'react';

type InputComponentProps = {
  value?: string;
  onChange?: ChangeEventHandler;
};

type InputRefType = HTMLInputElement;

const InputComponent = forwardRef<InputRefType, InputComponentProps>(
  ({ value, onChange }, ref) => (
    <input ref={ref} value={value} onChange={onChange} />
  ),
);

const SmallForm = (): JSX.Element => {
  const inputRef = createRef<InputRefType>();

  const onButtonClick = () => {
    inputRef.current?.focus();
  };

  return (
    <>
      <button type="button" onClick={onButtonClick}>
        Focus to input
      </button>
      <InputComponent ref={inputRef} />
    </>
  );
};

Here is a step-by-step explanation of what happens in the above example:

1. We create a React ref by calling createRef and assign it to a ref variable with InputRefType type.
2. We pass our ref down to <InputComponent ref={ref}> by specifying it as a JSX attribute.
3. React passes the ref to the (props, ref) => ... function inside forwardRef as a second argument.
4. We forward this ref argument down to <input ref={ref}> by specifying it as a JSX attribute.
5. When the ref is attached, ref.current will point to the <input> DOM node.