File size: 2,047 Bytes
1e92f2d | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 | 'use client'
import Link from 'next/link'
import * as React from 'react'
import {
useCallback,
useState,
type RefCallback,
type Ref,
type ComponentPropsWithRef,
type ReactNode,
} from 'react'
export default function Page() {
return (
<>
<h1>Home</h1>
<ToggleVisibility>
<Link href="/link-target" legacyBehavior>
<AnchorThatDoesRefMerging id="test-link">
Go to /link-target
</AnchorThatDoesRefMerging>
</Link>
</ToggleVisibility>
</>
)
}
function ToggleVisibility({ children }: { children: ReactNode }) {
const [isVisible, setIsVisible] = useState(true)
return (
<>
<div>
<button type="button" onClick={() => setIsVisible((prev) => !prev)}>
{isVisible ? 'Hide content' : 'Show content'}
</button>
</div>
{isVisible ? children : null}
</>
)
}
function AnchorThatDoesRefMerging({
ref,
children,
...anchorProps
}: ComponentPropsWithRef<'a'>) {
const customRef: RefCallback<HTMLAnchorElement> = useCallback((el) => {
if (el) {
console.log('hello friends i am here')
} else {
console.log('goodbye friends i am gone')
}
}, [])
const finalRef = useBuggyRefMerge(customRef, ref ?? null)
return (
<a ref={finalRef} {...anchorProps}>
{children}
</a>
)
}
/** A ref-merging function that doesn't account for cleanup refs (added in React 19)
* https://react.dev/blog/2024/12/05/react-19#cleanup-functions-for-refs
*/
function useBuggyRefMerge<TElement>(
refA: Ref<TElement>,
refB: Ref<TElement>
): RefCallback<TElement> {
return useCallback(
(current: TElement | null) => {
for (const ref of [refA, refB]) {
if (!ref) {
continue
}
if (typeof ref === 'object') {
ref.current = current
} else {
// BUG!!!
// This would work in 18, but in 19 it can return a cleanup which will get swallowed here
ref(current)
}
}
},
[refA, refB]
)
}
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