data-pager

Hommage to Data::Pager

data-pager is a simple data pager based on Data::Page , written for the exact same reasons:

When searching through large amounts of data, it is often the case that a result set is returned that is larger than we want to display on one page. This results in wanting to page through various pages of data. The maths behind this is unfortunately fiddly, hence this module.

The main concept is that you pass in the number of total entries, the number of entries per page, and the current page number. You can then call methods to find out how many pages of information there are, and what number the first and last entries on the current page really are.

For example, say we wished to page through the integers from 1 to 100 with 20 entries per page. The first page would consist of 120, the second page from 2140, the third page from 4160, the fourth page from 6180 and the fifth page from 81100. This module would help you work this out.

I'd also like to refer to that joke about off by one errors.

Changelog

• 27/10/2013 initial release
• 02/11/2013 off-by-one error in "pager.last" logic

Installation

npm install data-pager

Example

    var Pager = require('data-pager'),
        assert = require('assert');

    var total = 10,
        perpage = 3,
        current = 1;

    var pager = new Pager(total, perpage, current);

    assert.equal(pager.total, total, 'total: value was set in constructor');
    assert.equal(pager.perpage, perpage, 'perpage: value was set in constructor');
    assert.equal(pager.last, 4);

    // sets the page to page 4
    pager.page = 4;

    assert.equal( pager.page, 4 );

    assert.equal( pager.page,  4);
    assert.equal( pager.first,  9);
    assert.equal( pager.last,  9);
    assert.equal( pager.entries,  1);
    assert.equal( pager.skip,  9);
    assert.equal( pager.previous,  3);
    assert.equal( pager.next,  null);
    assert.equal( pager.nextPages(),  []);
    assert.equal( pager.previousPages(),  [2, 3]);

Methods

total

Sets or gets the total entries in this set

    pager.total = 42;
    assert.equal( pager.perpage, 42 );

Returns

Number, value Total entries in this set

perpage

Sets or gets the entries perpage

    pager.perpage = 5;
    assert.equal( pager.perpage, 5 );

Returns

Number, entries Total entries per page

page

Sets or gets the current page

Returns

Number, page Current page

entriesOnPage

Returns

Number, entries Number of entries on this page

first

Returns

Number, first First page (always 1)

last

Returns

Number, last Last page

previous

Returns

Number, prev Previous page, or null if this is the first page

next

Returns

Number, next Next page, or null if this is the last page

skip

Returns

Number, skip Number of entries to skip from the database

firstEntry

Returns

Number, entry Number of the first entry on the current page

lastEntry

Returns

Number, entry Number of the last entry on the current page

previousPages

List n previous pages before this page

Returns

Array, pages Array with page numbers

nextPages

List n previous pages after this page, excluding the last page

Returns

Array, pages Array with page numbers