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Merge pull request #4436 from preactjs/ref-cleanup
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feat: support ref cleanup functions
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marvinhagemeister authored Jul 7, 2024
2 parents db0f4f2 + 7bb245a commit 212b1f6
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Showing 3 changed files with 51 additions and 4 deletions.
18 changes: 15 additions & 3 deletions src/diff/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -554,14 +554,26 @@ function diffElementNodes(

/**
* Invoke or update a ref, depending on whether it is a function or object ref.
* @param {Ref<any>} ref
* @param {Ref<any> & { _unmount?: unknown }} ref
* @param {any} value
* @param {VNode} vnode
*/
export function applyRef(ref, value, vnode) {
try {
if (typeof ref == 'function') ref(value);
else ref.current = value;
if (typeof ref == 'function') {
let hasRefUnmount = typeof ref._unmount == 'function';
if (hasRefUnmount) {
// @ts-ignore TS doesn't like moving narrowing checks into variables
ref._unmount();
}

if (!hasRefUnmount || value != null) {
// Store the cleanup function on the function
// instance object itself to avoid shape
// transitioning vnode
ref._unmount = ref(value);
}
} else ref.current = value;
} catch (e) {
options._catchError(e, vnode);
}
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5 changes: 4 additions & 1 deletion src/internal.d.ts
Original file line number Diff line number Diff line change
Expand Up @@ -126,7 +126,10 @@ declare global {
// We use the `current` property to differentiate between the two kinds of Refs so
// internally we'll define `current` on both to make TypeScript happy
type RefObject<T> = { current: T | null };
type RefCallback<T> = { (instance: T | null): void; current: undefined };
type RefCallback<T> = {
(instance: T | null): void | (() => void);
current: undefined;
};
type Ref<T> = RefObject<T> | RefCallback<T>;

export interface VNode<P = {}> extends preact.VNode<P> {
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32 changes: 32 additions & 0 deletions test/browser/refs.test.js
Original file line number Diff line number Diff line change
Expand Up @@ -715,4 +715,36 @@ describe('refs', () => {
render(<App />, scratch);
render(<App show />, scratch);
});

it('should call ref cleanup on unmount', () => {
const cleanup = sinon.spy();
const ref = sinon.spy(() => cleanup);

function App({ show = false }) {
return <div>{show && <p ref={ref}>hello</p>}</div>;
}

render(<App show />, scratch);
render(<App />, scratch);

expect(cleanup).to.be.calledOnce;

// Ref should not be called with `null` when cleanup is present
expect(ref).to.be.calledOnce;
expect(ref).not.to.be.calledWith(null);
});

it('should call ref cleanup when ref changes', () => {
const cleanup = sinon.spy();

function App({ show = false, count = 0 }) {
return <div>{show && <p ref={() => cleanup}>hello {count}</p>}</div>;
}

render(<App show />, scratch);
render(<App show count={1} />, scratch);

// Cleanup should be invoked whenever ref function changes
expect(cleanup).to.be.calledOnce;
});
});

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