useImperativeHandle

useImperativeHandle is a React Hook lets you customize the handle exposed as a ref.

useImperativeHandle(ref, createHandle, dependencies?)

Usage
- Exposing a custom ref handle to the parent component
- Exposing your own imperative methods
Reference
- useImperativeHandle(ref, createHandle, dependencies?)

Usage

Exposing a custom ref handle to the parent component

By default, components don’t expose their DOM nodes to parent components. For example, if you want the parent component of MyInput to have access to the <input> DOM node, you have to opt in with forwardRef:

import { forwardRef } from 'react';

const MyInput = forwardRef(function MyInput(props, ref) {
  return <input {...props} ref={ref} />;
});

With the code above, a ref to MyInput will receive the <input> DOM node. However, you can expose a custom value instead. To customize the exposed handle, call useImperativeHandle at the top level of your component:

import { forwardRef, useImperativeHandle } from 'react';

const MyInput = forwardRef(function MyInput(props, ref) {
  useImperativeHandle(ref, () => {
    return {
      // ... your methods ...
    };
  }, []);

  return <input {...props} />;
});

Note that in the code above, the ref is no longer forwarded to the <input>.

For example, suppose you don’t want to expose the entire <input> DOM node, but you want to expose two of its methods: focus and scrollIntoView. To do this, keep the real browser DOM in a separate ref. Then use useImperativeHandle to expose a handle with only the methods that you want the parent component to call:

import { forwardRef, useRef, useImperativeHandle } from 'react';

const MyInput = forwardRef(function MyInput(props, ref) {
  const inputRef = useRef(null);

  useImperativeHandle(ref, () => {
    return {
      focus() {
        inputRef.current.focus();
      },
      scrollIntoView() {
        inputRef.current.scrollIntoView();
      },
    };
  }, []);

  return <input {...props} ref={inputRef} />;
});

Now, if the parent component gets a ref to MyInput, it will be able to call the focus and scrollIntoView methods on it. However, it will not have full access to the underlying <input> DOM node.

Fork

import { useRef } from 'react';
import MyInput from './MyInput.js';

export default function Form() {
  const ref = useRef(null);

  function handleClick() {
    ref.current.focus();
    // This won't work because the DOM node isn't exposed:
    // ref.current.style.opacity = 0.5;
  }

  return (
    <form>
      <MyInput label="Enter your name:" ref={ref} />
      <button type="button" onClick={handleClick}>
        Edit
      </button>
    </form>
  );
}

Exposing your own imperative methods

The methods you expose via an imperative handle don’t have to match the DOM methods exactly. For example, the Post component in the example below exposes a scrollAndFocusAddComment method via an imperative handle. This lets the parent Page scroll the list of comments and focus the input field when you click the button:

Fork

import { useRef } from 'react';
import Post from './Post.js';

export default function Page() {
  const postRef = useRef(null);

  function handleClick() {
    postRef.current.scrollAndFocusAddComment();
  }

  return (
    <>
      <button onClick={handleClick}>
        Write a comment
      </button>
      <Post ref={postRef} />
    </>
  );
}

Atención

Do not overuse refs. You should only use refs for imperative behaviors that you can’t express as props: for example, scrolling to a node, focusing a node, triggering an animation, selecting text, and so on.

If you can express something as a prop, you should not use a ref. For example, instead of exposing an imperative handle like { open, close } from a Modal component, it is better to take isOpen as a prop like <Modal isOpen={isOpen} />. Effects can help you expose imperative behaviors via props.

Reference

`useImperativeHandle(ref, createHandle, dependencies?)`

Call useImperativeHandle at the top level of your component to customize the ref handle it exposes:

import { forwardRef, useImperativeHandle } from 'react';

const MyInput = forwardRef(function MyInput(props, ref) {
  useImperativeHandle(ref, () => {
    return {
      // ... your methods ...
    };
  }, []);
  // ...

See more examples.

Parameters

ref: The ref you received as the second argument from the forwardRef render function.
createHandle: A function that takes no arguments and returns the ref handle you want to expose. The ref handle you return have any type. Usually, you will return an object with the methods you want to expose.
optional dependencies: The list of all reactive values referenced inside of the createHandle code. Reactive values include props, state, and all the variables and functions declared directly inside your component body. If your linter is configured for React, it will verify that every reactive value is correctly specified as a dependency. The list of dependencies must have a constant number of items and be written inline like [dep1, dep2, dep3]. React will compare each dependency with its previous value using the Object.is comparison algorithm. If a re-render resulted in a change to some dependency, or if you did not specify the dependencies at all, your createHandle function will re-execute, and the newly created handle will be assigned to the ref.

Returns

useImperativeHandle returns undefined.

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