What's the Difference Between `Useref` and `Createref`?

Question

I was going through the hooks documentation when I stumbled upon useRef.

Looking at their example…

function TextInputWithFocusButton() {
  const inputEl = useRef(null);
  const onButtonClick = () => {
    // `current` points to the mounted text input element
    inputEl.current.focus();
  };
  return (
    <>
      <input ref={inputEl} type="text" />
      <button onClick={onButtonClick}>Focus the input</button>
    </>
  );
}

…it seems like useRef can be replaced with createRef.

function TextInputWithFocusButton() {
  const inputRef = createRef(); // what's the diff?
  const onButtonClick = () => {
    // `current` points to the mounted text input element
    inputRef.current.focus();
  };
  return (
    <>
      <input ref={inputRef} type="text" />
      <button onClick={onButtonClick}>Focus the input</button>
    </>
  );
}

Why do I need a hook for refs? Why does useRef exist?

Accepted Answer

The difference is that createRef will always create a new ref. In a class-based component, you would typically put the ref in an instance property during construction (e.g. this.input = createRef()). You don't have this option in a function component. useRef takes care of returning the same ref each time as on the initial rendering.

Here's an example app demonstrating the difference in the behavior of these two functions:

import React, { useRef, createRef, useState } from "react";
import ReactDOM from "react-dom";

function App() {
  const [renderIndex, setRenderIndex] = useState(1);
  const refFromUseRef = useRef();
  const refFromCreateRef = createRef();
  if (!refFromUseRef.current) {
    refFromUseRef.current = renderIndex;
  }
  if (!refFromCreateRef.current) {
    refFromCreateRef.current = renderIndex;
  }
  return (
    <div className="App">
      Current render index: {renderIndex}
      <br />
      First render index remembered within refFromUseRef.current:
      {refFromUseRef.current}
      <br />
      First render index unsuccessfully remembered within
      refFromCreateRef.current:
      {refFromCreateRef.current}
      <br />
      <button onClick={() => setRenderIndex(prev => prev + 1)}>
        Cause re-render
      </button>
    </div>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Answer 2

Must Read

tldr

A ref is a plain JS object { current: <some value> }.

React.createRef() is a factory returning a ref { current: null } - no magic involved.

useRef(initValue) also returns a ref { current: initValue } akin to React.createRef(). Besides, it memoizes this ref to be persistent across multiple renders in a function component.

It is sufficient to use React.createRef in class components, as the ref object is assigned to an instance variable, hence accessible throughout the component and its lifecyle:

this.myRef = React.createRef(); // stores ref in "mutable" this context (class)

useRef(null) basically is equivalent to useState(React.createRef())[0] ¹.

What's the Difference Between `Useref` and `Createref`?

6 Answers

Must Read

tldr

Sarah Jenkins