21 lines
693 B
Markdown
21 lines
693 B
Markdown
# Using `meta` in comparison
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Sometimes a "pure" equality between two objects is insufficient, because the comparison relies on some external state. While these kinds of scenarios should generally be avoided, it is possible to handle them with a custom internal comparator that checks `meta` values.
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```ts
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import { createCustomEqual } from 'fast-equals';
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interface Meta {
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value: string;
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}
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const meta: Meta = { value: 'baz' };
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const deepEqual = createCustomEqual<Meta>({
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createInternalComparator:
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(compare) => (a, b, _keyA, _keyB, _parentA, _parentB, state) =>
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compare(a, b, state) || a === state.meta.value || b === state.meta.value,
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createState: () => ({ meta }),
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});
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```
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