useRef

const ref = useRef(initialValue)

• Reference
  • useRef(initialValue)
• Usage
  • Referencing a value with a ref
  • Manipulating the DOM with a ref
  • Avoiding recreating the ref contents
• Troubleshooting
  • I can’t get a ref to a custom component

Reference

useRef(initialValue)

Call useRef at the top level of your component to declare a ref.

import { useRef } from 'react';

function MyComponent() {
  const intervalRef = useRef(0);
  const inputRef = useRef(null);
  // ...

See more examples below.

Parameters

• initialValue: The value you want the ref object’s current property to be initially. It can be a value of any type. This argument is ignored after the initial render.

Returns

useRef returns an object with a single property:

• current: Initially, it’s set to the initialValue you have passed. You can later set it to something else. If you pass the ref object to React as a ref attribute to a JSX node, React will set its current property.

On the next renders, useRef will return the same object.

Caveats

• You can mutate the ref.current property. Unlike state, it is mutable. However, if it holds an object that is used for rendering (for example, a piece of your state), then you shouldn’t mutate that object.
• When you change the ref.current property, React does not re-render your component. React is not aware of when you change it because a ref is a plain JavaScript object.
• Do not write or read ref.current during rendering, except for initialization. This makes your component’s behavior unpredictable.
• In Strict Mode, React will call your component function twice in order to help you find accidental impurities. This is development-only behavior and does not affect production. Each ref object will be created twice, but one of the versions will be discarded. If your component function is pure (as it should be), this should not affect the behavior.

Usage

Referencing a value with a ref

Call useRef at the top level of your component to declare one or more refs.

import { useRef } from 'react';

function Stopwatch() {
  const intervalRef = useRef(0);
  // ...

useRef returns a ref object with a single current property initially set to the initial value you provided.

On the next renders, useRef will return the same object. You can change its current property to store information and read it later. This might remind you of state, but there is an important difference.

Changing a ref does not trigger a re-render. This means refs are perfect for storing information that doesn’t affect the visual output of your component. For example, if you need to store an interval ID and retrieve it later, you can put it in a ref. To update the value inside the ref, you need to manually change its current property:

function handleStartClick() {
  const intervalId = setInterval(