49 lines
1.5 KiB
TypeScript
49 lines
1.5 KiB
TypeScript
import { computed, toValue } from 'vue';
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import type { ComputedRef, MaybeRefOrGetter } from 'vue';
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export type UseArrayFindLastReturn<T = unknown>
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= ComputedRef<T | undefined>;
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/**
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* `Array.prototype.findLast` polyfill for runtimes older than ES2023.
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*/
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function findLast<T>(
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array: T[],
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fn: (element: T, index: number, array: T[]) => unknown,
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): T | undefined {
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let index = array.length;
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while (index-- > 0) {
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const element = array[index]!;
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if (fn(element, index, array))
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return element;
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}
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return undefined;
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}
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const hasNativeFindLast = typeof Array.prototype.findLast === 'function';
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/**
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* @name useArrayFindLast
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* @category Array
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* @description Reactive `Array.prototype.findLast`.
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*
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* @param {MaybeRefOrGetter<MaybeRefOrGetter<T>[]>} list The source array (items can be reactive)
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* @param {(element: T, index: number, array: T[]) => unknown} fn Predicate testing each element
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* @returns {UseArrayFindLastReturn<T>} The last matching element, or `undefined` if none match
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*
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* @example
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* const list = ref([1, 2, 3, 4]);
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* const found = useArrayFindLast(list, n => n % 2 === 0); // 4
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*
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* @since 0.0.14
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*/
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export function useArrayFindLast<T>(
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list: MaybeRefOrGetter<Array<MaybeRefOrGetter<T>>>,
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fn: (element: T, index: number, array: T[]) => unknown,
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): UseArrayFindLastReturn<T> {
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return computed(() => {
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const resolved = toValue(list).map(item => toValue(item));
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return hasNativeFindLast ? resolved.findLast(fn) : findLast(resolved, fn);
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});
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}
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