React - Forwarding multiple refs

Question

I have a SideNav component that contains dynamically created links that need to scroll to a corresponding header in an adjacent html table (InfoTable). I've tried multiple different ways of accomplishing this to no avail.

export default class Parent extends Component {
  state = {
    categories: [],
  }

  scrollToHeader = (tableRefString) => {
    // Function to pass to SideNav to access refs in InfoTable
    this[tableRefString].scrollIntoView({ block: 'start' });
  }

  render() {
    return (
      <div>
        <SideNav
          categories={this.state.categories}
          scrollToHeader={this.scrollToHeader} />
        <InfoTable
          categories={this.state.categories} />
      </div>
    );
  }
}

export default class InfoTable extends Component {
  render() {
    return (
      <div>
        <table>
          <tbody>
            {this.props.categories.map(category => (
              <>
                // Forward the ref through InfoTableHeader to be set on the parent DOM node of each InfoTableHeader
                <InfoTableHeader />
                {category.inputs.map(input => <InfoTableRow />)}
              </>
            ))}
          </tbody>
        </table>
      </div>
    );
  }
}

In order to click a link on SideNav and scroll to the corresponding header on InfoTable, I believe that I need to forward refs that are dynamically created on Parent based on names in my categories array and set these refs to the DOM nodes for each header in InfoTable. From there I would pass a function to SideNav that could access the refs in Parent in order to scroll to the header.

• How can I go about forwarding multiple refs at once to my InfoTable component?
• Is there a cleaner way to accomplish what I'm trying to do? I've looked into React.findDOMNode() but refs seem to be the better option.

Answer 1

I know there is an already accepted answer, and while I find @nicholas-haley's solution acceptable. I think a better way to go about it would be to use the built-in useImperativeHandle hook.

IMPORTANT: The React Hooks Api is available as of

• react@16.8.0 and later
• react-native@0.59.0 and later

The React hooks API Docs state:

useImperativeHandle customizes the instance value that is exposed to parent components when using ref. As always, imperative code using refs should be avoided in most cases. useImperativeHandle should be used with `forwardRef

This note is followed by the following example:

function FancyInput(props, ref) {
  const inputRef = useRef();
  useImperativeHandle(ref, () => ({
    focus: () => {
      inputRef.current.focus();
    }
  }));
  return <input ref={inputRef} ... />;
}
FancyInput = forwardRef(FancyInput);

Thus, in my opinion, a much cleaner solution would be to delegate the needed refs through the useImperativeHandle hook.

This way there is no need for a special ref syntax, and the component can simply return a specific type of a FatherRef; Example:

// LabelInput.js
function LabelInput(props, ref) {
    const labelRef = useRef();
    const inputRef = useRef();

    useImperativeHandle(ref, () => ({
      focus: () => {
       inputRef.current.focus();
      },
      get input() {
          return inputRef.current;
      },
      get label() {
          return labelRef.current;
      },
      // ... whatever else one may need
    }));
    return (
      <div>
        <label ref={labelRef} ... />
        <input ref={inputRef} ... />;
      </div>
    )
}
LabelInput = forwardRef(LabelInput);

function MyScreen() {
   const labelInputRef = useRef();

   const onClick = useCallback(
    () => {
//       labelInputRef.current.focus(); // works
//       labelInputRef.current.input.focus(); // works
// ... etc
    },
    []
   );

   return (
     ...
      <LabelInput ref={labelInputRef} ... />
     ....
   )
}

EDIT: Plus while the old doc is still totally relevant for this usecase, here is also the new link https://react.dev/reference/react/useImperativeHandle#exposing-your-own-imperative-methods

Answer 2

I had a similar situation where I needed multiple refs to be forwarded to the child of my Parent component.

I still have not found an elegant solution, however you might try passing your refs as an object, and destructuring within the forwardRef callback:

// Parent
ref={{
    ref1: this.ref1,
    ref2: this.ref2
}}

---

// Child
export default React.forwardRef((props, ref) => {
  const { ref1, ref2 } = ref;

  return (
    <Child1
      {...props}
      ref={ref1}
    />
    <Child2
      {...props}
      ref={ref2}
    />
  );
});

I'm not a big fan of the naming here (I'd prefer ref to be called refs), but this works in case you're in a pinch.

EDIT:

In 2020 I believe @samer-murad's answer is the best solution to this problem.

Answer 3

I actually just picked this up from react-hook-form, but they presented a nice way to share ref and assign multiple refs at once:

<input name="firstName" ref={(e) => {
  register(e) // use ref for register function
  firstNameRef.current = e // and you can still assign to ref
}} />

Answer 4

I still don't understand what goes on in that ref property, but the following React source code typeof type.render === 'function' + the other answers led me to try passing a function of hoisted refs from parent, and it works!

class Child extends React.Component {
  render() {
    return (
      <div>
        <div
          ref={this.props.pa}
          style={this.props.style}
          onClick={async () => {
            this.storeAuth(...this.props.storableAuth);
            this.props.clearStore();
          }}
        />
        <div
          ref={this.props.fwd}
          style={this.props.style}
          onClick={async () => {
            this.props.onStart();
            const res = await this.getUserInfo(verbose, auth, storedAuth);
            if (res === "login?") this.props.onPromptToLogin();
            if (res) this.props.onFinish(); //res.isAnonymous
          }}
        />
      </div>
    );
  }
}

export default React.forwardRef((props, getRefs) => {
  const { pa, fwd } = props.getRefs();
  return <Child fwd={fwd} pa={pa} {...props} />;
});


class Parent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {};
    this.pa = React.createRef();
    this.fwd = React.createRef();
  }
  render() {
    return (
      <Child
        getRefs={() => {
          return {
            pa: this.pa,
            fwd: this.fwd
          };
        }}
        storableAuth={this.state.storableAuth}//[]
        clearAuth={() => this.setState({ storableAuth: null })}
      />
    );
  }
}

Answer 5

This is not exactly what the author of this question asked, but this title could feet to this question as well: how do I allow developers using my React component to pass a ref if I pass ref internally in my component also (mean, passing multiple refs that will get a ref for this element),

this is the solution i came with:

import { useState, useRef } from "react";

export default function App() {
  const [, render] = useState({});
  const reRender = () => render({});

  const divRef = useRef();
  console.log("App", divRef);
  return <Component reRender={reRender} passPropsToDiv={{ ref: divRef }} />;
}

const Component = ({ passPropsToDiv, reRender }) => {
  const div1Ref = useRef();
  const { ref: extraRef = null, ...passPropsToDivNoRef } = passPropsToDiv ?? {};
  extraRef.current = div1Ref.current;
  console.log("Component", div1Ref);

  return (
    <div className="App">
      <div ref={div1Ref} {...passPropsToDivNoRef}>
        i will have a ref
      </div>
      <button onClick={reRender}>reRender</button>
    </div>
  );
};

codesandbox: https://codesandbox.io/s/react-use-pass-multiple-refs-legm7p?file=/src/App.js

Answer 6

You can pass multiple refs via the forwardRef() function by using the useImperativeHandle() hook. This function allows you to define functions to expose to the parent element, using the second argument of useImperativeHandle().

Here's an example code for your Child component with forwardRef() and useImperativeHandle() to pass the three refs to the parent element:

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

export interface ChildRef {
  containerRef: HTMLDivElement | null;
  segmentsRef: (HTMLDivElement | null)[];
  cursorRef: HTMLDivElement | null;
}

export interface IChildProps {
  // props of your component
}

const Child = forwardRef<ChildRef, IChildProps>((props, ref) => {
  const containerRef = useRef<HTMLDivElement | null>(null);
  const segmentsRef = useRef<(HTMLDivElement | null)[]>([]);
  const cursorRef = useRef<HTMLDivElement | null>(null);

  useImperativeHandle(ref, () => ({
    containerRef: containerRef.current,
    segmentsRef: segmentsRef.current,
    cursorRef: cursorRef.current,
  }));

  // rest of your component code
});

export default Child;

Now in the parent component, you can use useRef() to create a reference to the Child element, and pass this reference to Child via the ref prop.

Here's an example code for your Parent component:

import React, { useRef } from 'react';
import Child, { ChildRef } from './Child';

const Parent = () => {
  const childRef = useRef<ChildRef>(null);

  const handleClick = () => {
    console.log(childRef.current?.containerRef);
    console.log(childRef.current?.segmentsRef);
    console.log(childRef.current?.cursorRef);
  };

  return (
    <div>
      <button onClick={handleClick}>Log refs</button>
      <Child ref={childRef} />
    </div>
  );
};

export default Parent;

I hope this helps!