@tldraw/editor/dist-esm/lib/hooks/useEvent.mjs.map

tldraw infinite canvas SDK (editor).

{
  "version": 3,
  "sources": ["../../../src/lib/hooks/useEvent.tsx"],
  "sourcesContent": ["import { useAtom } from '@tldraw/state-react'\nimport { assert } from '@tldraw/utils'\nimport { useCallback, useDebugValue, useLayoutEffect, useRef } from 'react'\n\n/**\n * Allows you to define event handlers that can read the latest props/state but has a stable\n * function identity.\n *\n * These event callbacks may not be called in React render functions! An error won't be thrown, but\n * in the real implementation it would be!\n *\n * Uses a modified version of the user-land implementation included in the [`useEvent()` RFC][1].\n * Our version until such a hook is available natively.\n *\n * The RFC was closed on 27 September 2022, the React team plans to come up with a new RFC to\n * provide similar functionality in the future. We will migrate to this functionality when\n * available.\n *\n * IMPORTANT CAVEAT: You should not call event callbacks in layout effects of React component\n * children! Internally this hook uses a layout effect and parent component layout effects run after\n * child component layout effects. Use this hook responsibly.\n *\n * [1]: https://github.com/reactjs/rfcs/pull/220\n *\n * @internal\n */\nexport function useEvent<Args extends Array<unknown>, Result>(\n\thandler: (...args: Args) => Result\n): (...args: Args) => Result {\n\tconst handlerRef = useRef<(...args: Args) => Result>()\n\n\t// In a real implementation, this would run before layout effects\n\tuseLayoutEffect(() => {\n\t\thandlerRef.current = handler\n\t})\n\n\tuseDebugValue(handler)\n\n\treturn useCallback((...args: Args) => {\n\t\t// In a real implementation, this would throw if called during render\n\t\tconst fn = handlerRef.current\n\t\tassert(fn, 'fn does not exist')\n\t\treturn fn(...args)\n\t}, [])\n}\n\n/**\n * like {@link useEvent}, but for use in reactive contexts - when the handler function changes, it\n * will invalidate any reactive contexts that call it.\n * @internal\n */\nexport function useReactiveEvent<Args extends Array<unknown>, Result>(\n\thandler: (...args: Args) => Result\n): (...args: Args) => Result {\n\tconst handlerAtom = useAtom<(...args: Args) => Result>('useReactiveEvent', () => handler)\n\n\t// In a real implementation, this would run before layout effects\n\tuseLayoutEffect(() => {\n\t\thandlerAtom.set(handler)\n\t})\n\n\tuseDebugValue(handler)\n\n\treturn useCallback(\n\t\t(...args: Args) => {\n\t\t\t// In a real implementation, this would throw if called during render\n\t\t\tconst fn = handlerAtom.get()\n\t\t\tassert(fn, 'fn does not exist')\n\t\t\treturn fn(...args)\n\t\t},\n\t\t[handlerAtom]\n\t)\n}\n"],
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