paging-algorithm/dist/index.js

Pagination algorithm

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
function getRange(start, end) {
    return [...Array(end - start + 1)].map((_, i) => start + i);
}
exports.getRange = getRange;
function getPageInfo(params) {
    const { limit, pageCount, total, page } = params;
    const totalPages = Math.ceil(total / limit);
    const totalResults = total;
    let currentPage = page;
    if (currentPage < 1) {
        currentPage = 1;
    }
    if (currentPage > totalPages) {
        currentPage = totalPages;
    }
    let firstPage = Math.max(1, currentPage - Math.floor(pageCount / 2));
    let lastPage = Math.min(totalPages, currentPage + Math.floor(pageCount / 2));
    if (lastPage - firstPage + 1 < pageCount) {
        if (currentPage < totalPages / 2) {
            lastPage = Math.min(totalPages, lastPage + (pageCount - (lastPage - firstPage)));
        }
        else {
            firstPage = Math.max(1, firstPage - (pageCount - (lastPage - firstPage)));
        }
    }
    if (lastPage - firstPage + 1 > pageCount) {
        if (currentPage > totalPages / 2) {
            firstPage = firstPage + 1;
        }
        else {
            lastPage = lastPage - 1;
        }
    }
    const pages = Math.min(lastPage - firstPage + 1, totalPages);
    const previousPage = currentPage - 1;
    const nextPage = currentPage + 1;
    const hasPreviousPage = currentPage > 1;
    const hasNextPage = currentPage < totalPages;
    const firstResult = limit * (currentPage - 1);
    const lastResult = limit * currentPage - 1;
    const results = Math.min(lastResult - firstResult + 1, totalResults);
    return {
        totalPages,
        pages,
        currentPage,
        firstPage,
        lastPage,
        previousPage,
        nextPage,
        hasPreviousPage,
        hasNextPage,
        totalResults,
        results,
        firstResult,
        lastResult
    };
}
exports.getPageInfo = getPageInfo;
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