@primer/react/dist/hooks/useMergedRefs.d.ts

An implementation of GitHub's Primer Design System using React

import type { ForwardedRef, Ref as StandardRef } from 'react';
/**
 * Combine two refs of matching type (typically an external or forwarded ref and an internal `useRef` object or
 * callback ref).
 *
 * If you need to combine more than two refs (what are you doing?) just nest the hook:
 * `useMergedRefs(refA, useMergedRefs(refB, refC))`
 *
 * @param refA First ref to merge. The order is not important.
 * @param refB Second ref to merge. The order is not important.
 * @returns A new ref which must be passed to the relevant child component. **Important**: do not pass `refA` or
 * `refB` to the component!
 *
 * @example
 * // React 18
 * const Example = forwardRef<HTMLButtonElement, {}>((props, forwardedRef) => {
 *  const ref = useRef<HTMLButtonElement>(null)
 *  const combinedRef = useMergedRefs(forwardedRef, ref)
 *
 *  return <button ref={combinedRef} />
 * })
 *
 * @example
 * // React 19
 * const Example = ({ref: externalRef}: {ref?: Ref<HTMLButtonElement>}) => {
 *  const ref = useRef<HTMLButtonElement>(null)
 *  const combinedRef = useMergedRefs(externalRef, ref)
 *
 *  return <button ref={combinedRef} />
 * }
 */
export declare function useMergedRefs<T>(refA: Ref<T | null>, refB: Ref<T | null>): (value: T | null) => () => void;
type CleanupFunction = () => void;
/**
 * React 19 supports callback refs that can return a cleanup function. If a cleanup function is returned, the
 * cleanup is called on unmount **instead** of setting the ref to null.
 */
type React19RefCallback<T> = {
    bivarianceHack(instance: T): void | CleanupFunction;
}['bivarianceHack'];
/**
 * Supporting React 18 and 19 while alleviating the need for any hacks or casts in consumers:
 * - `ForwardedRef` from the React 18 `forwardRef` HOC
 * - `React19RefCallback` for callback refs that can return a cleanup function (this is included in `Ref` in React 19
 *   but not in 18)
 * - `Ref` for standard refs from `useRef` or passed in as React 19 prop
 * - `undefined` to allow for easy use of optional `ref` props in React 19
 */
type Ref<T> = ForwardedRef<T> | React19RefCallback<T> | StandardRef<T> | undefined;
export {};
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