49 lines
1.2 KiB
Markdown
49 lines
1.2 KiB
Markdown
# Non-standard properties
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Sometimes, objects require a comparison that extend beyond its own keys, or even its own properties or symbols. Using a custom object comparator with `createCustomEqual` allows these kinds of comparisons.
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```ts
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import { createCustomEqual } from 'fast-equals';
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import type { TypeEqualityComparator } from 'fast-equals';
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type AreObjectsEqual = TypeEqualityComparator<Record<any, any>, undefined>;
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class HiddenProperty {
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visible: boolean;
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#hidden: string;
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constructor(value: string) {
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this.visible = true;
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this.#hidden = value;
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}
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get hidden() {
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return this.#hidden;
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}
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}
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function createAreObjectsEqual(
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areObjectsEqual: AreObjectsEqual,
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): AreObjectsEqual {
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return function (a, b, state) {
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if (!areObjectsEqual(a, b, state)) {
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return false;
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}
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const aInstance = a instanceof HiddenProperty;
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const bInstance = b instanceof HiddenProperty;
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if (aInstance || bInstance) {
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return aInstance && bInstance && a.hidden === b.hidden;
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}
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return true;
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};
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}
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const deepEqual = createCustomEqual({
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createCustomConfig: ({ areObjectsEqual }) =>
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createAreObjectsEqual(areObjectsEqual),
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});
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```
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