How to focus something on next render with React Hooks - reactjs

Question

I'm playing with hooks, and I'm trying to do the following:
import React, { useState, useRef } from 'react';
const EditableField = () => {
const [isEditing, setEditing] = useState(false);
const inputRef = useRef();
const toggleEditing = () => {
setEditing(!isEditing);
if (isEditing) {
inputRef.current.focus();
}
};
return (
<>
{isExpanded && <input ref={inputRef} />}
<button onClick={toggleEditing}>Edit</button>
</>
);
};
This is going to fail, because current is null, since the component haven't re-rendered yet, and the input field is not yet rendered (and therefore can't be focused yet).
What is the right way to do this? I can use the usePrevious hook proposed in the React Hooks FAQ, but it seems like a painful workaround.
Is there a different way?

Answer 1

You can use the useEffect hook to run a function after every render when isEditing changed. In this function you can check if isEditing is true and focus the input.
Example
const { useState, useRef, useEffect } = React;
const EditableField = () => {
const [isEditing, setEditing] = useState(false);
const toggleEditing = () => {
setEditing(!isEditing);
};
const inputRef = useRef(null);
useEffect(() => {
if (isEditing) {
inputRef.current.focus();
}
}, [isEditing]);
return (
<div>
{isEditing && <input ref={inputRef} />}
<button onClick={toggleEditing}>Edit</button>
</div>
);
};
ReactDOM.render(<EditableField />, document.getElementById("root"));
<script src="https://unpkg.com/react#16.7.0-alpha.2/umd/react.production.min.js"></script>
<script src="https://unpkg.com/react-dom#16.7.0-alpha.2/umd/react-dom.production.min.js"></script>
<div id="root"></div>

Answer 2

I know the accepted answer covers the requested element in the above question.
But as an additional note, if you are using functional components, make use of React.forwardRef to pass down the reference to child components. It might be
definitely useful for someone who refers to this question later on.
In a more cleaner way, you can write your child component which accept the ref as given below:
const InputField = React.forwardRef((props, ref) => {
return (
<div className={props.wrapperClassName}>
<input
type={props.type}
placeholder={props.placeholder}
className={props.className}
name={props.name}
id={props.id}
ref={ref}/>
</div>
)
})

Answer 3

Or Simply use this component
import { FC, useEffect, useRef } from 'react'
export const FocusedInput: FC<JSX.IntrinsicElements['input']> = (props) => {
const inputRef = useRef<null | HTMLElement>(null)
useEffect(() => {
inputRef.current!.focus()
}, [])
return <input {...props} type="text" ref={inputRef as any} />
}