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Generic pagination service for calculating paginate essentials
/*
* Export as a type
*/
export const paginationService = {
getPager,
}
/*
* Get pager related data
*/
function getPager(
totalItems: number,
currentPage: number = 1,
pageSize: number = 10
) {
// calculate total pages
let totalPages = Math.ceil(totalItems / pageSize)
// ensure current page isn't out of range
if (currentPage < 1) {
currentPage = 1
} else if (currentPage > totalPages) {
currentPage = totalPages
}
let startPage: number, endPage: number
if (totalPages <= 10) {
// less than 10 total pages so show all
startPage = 1
endPage = totalPages
} else {
// more than 10 total pages so calculate start and end pages
if (currentPage <= 6) {
startPage = 1
endPage = 10
} else if (currentPage + 4 >= totalPages) {
startPage = totalPages - 9
endPage = totalPages
} else {
startPage = currentPage - 5
endPage = currentPage + 4
}
}
// calculate start and end item indexes
let startIndex = (currentPage - 1) * pageSize
let endIndex = Math.min(startIndex + pageSize - 1, totalItems - 1)
// create an array of pages to ng-repeat in the pager control
let pages = Array.from(Array(endPage + 1 - startPage).keys()).map(
(i) => startPage + i
)
// return object with all pager properties required by the view
return {
totalItems: totalItems,
currentPage: currentPage,
pageSize: pageSize,
totalPages: totalPages,
startPage: startPage,
endPage: endPage,
startIndex: startIndex,
endIndex: endIndex,
pages: pages,
}
}
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