| 1 | import { useRef } from 'react';
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| 2 | var dft = Symbol('default value sigil');
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| 3 | /**
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| 4 | * Exactly the same as `useRef` except that the initial value is set via a
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| 5 | * factroy function. Useful when the default is relatively costly to construct.
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| 6 | *
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| 7 | * ```ts
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| 8 | * const ref = useRefWithInitialValueFactory<ExpensiveValue>(() => constructExpensiveValue())
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| 9 | *
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| 10 | * ```
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| 11 | *
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| 12 | * @param initialValueFactory A factory function returning the ref's default value
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| 13 | * @category refs
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| 14 | */
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| 15 |
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| 16 | export default function useRefWithInitialValueFactory(initialValueFactory) {
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| 17 | var ref = useRef(dft);
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| 18 |
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| 19 | if (ref.current === dft) {
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| 20 | ref.current = initialValueFactory();
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| 21 | }
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| 22 |
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| 23 | return ref;
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| 24 | } |
| \ | No newline at end of file |