43 lines
1.2 KiB
TypeScript
43 lines
1.2 KiB
TypeScript
/**
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* Given the number of pages to display, the current page and the total pages,
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* returns the min and max index of the pages to display in the pagination component.
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*
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* @param {number} pagesToDisplay Maximum number of pages to display in the pagination component.
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* @param {number} currentPage Page currently visible.
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* @param {number} totalPages Total pages available.
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* @return {Object} Object containing the min and max index to display in the pagination component.
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*/
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type minMaxIndex = {
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minIndex: number | null;
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maxIndex: number | null;
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};
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export const getIndexes = (
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pagesToDisplay: number,
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currentPage: number,
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totalPages: number
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): minMaxIndex => {
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if ( totalPages <= 2 ) {
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return { minIndex: null, maxIndex: null };
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}
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const extraPagesToDisplay = pagesToDisplay - 1;
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const tentativeMinIndex = Math.max(
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Math.floor( currentPage - extraPagesToDisplay / 2 ),
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2
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);
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const maxIndex = Math.min(
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Math.ceil(
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currentPage +
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( extraPagesToDisplay - ( currentPage - tentativeMinIndex ) )
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),
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totalPages - 1
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);
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const minIndex = Math.max(
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Math.floor(
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currentPage - ( extraPagesToDisplay - ( maxIndex - currentPage ) )
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),
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2
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);
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return { minIndex, maxIndex };
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};
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