AppPaginator

A TypeScript/JavaScript class for pagination in a real-world web application. It
automatically batchinates the full dataset in case it's huge.
In the constructor you pass in a dataSource that returns data in batches that
contain multiple pages worth. (A batch is either the total amount of data you
want the app to have loaded in memory at once, or the total amount of data the
data source is willing to give you at once —— whichever is less. Tell
AppPaginator the batch size by setting the property itemsPerBatch.) When the
method set_currentPageNumber(num) is called, this class requests from
dataSource the batch that page is in. Then the items of the requested page
will be in the property currentPage.

Basic Usage

// Get an instance (see constructor for dataSource details):
let appPaginator = new AppPaginator(dataSource);

// Make sure itemsPerPage has the value you want:
appPaginator.itemsPerPage = 10;

appPaginator.itemsPerBatch = 200;

// Show the first page:
await appPaginator.set_currentPageNumber(1);
console.log(appPaginator.currentPage); // `[item1, item2, item3, item4,...]`

// The user performs a search to narrow down the dataset.
// You want the paginator to react to this, so you do a reset:
await appPaginator.reset();

Constructor

constructor(
    dataSource: {

        getBatch: (
            batchNumber: number, itemsPerBatch: number, isLastBatch: boolean
        ) => Promise<any[]>;
            // The number of items `getBatch()` returns must match `itemsPerBatch`.
            // If `isLastBatch` is true, it must only return the remaining items 
            // in the dataset and ignore itemsPerBatch.

        dataTotal: number;
            // `dataTotal`: number of items in entire dataset, not the batch.
            // This must stay accurate after actions that change the total, such 
            // as searches.
    }
)

Properties

itemsPerPage: number
    // Default is 25.

itemsPerBatch: number
    // Total number of items the app can have loaded in memory.
    // If your data source doesn't allow you to request batches the size of multiple
    // pages, set this to same value as this.itemsPerPage.
    // NOTE: if this isn't evenly divisible by this.itemsPerPage, its value is 
    // lowered until it is.

currentPageNumber: number // read-only

currentPage: any[] // read-only
    // All items in the current page.

totalPages: number // read-only

Methods

async set_currentPageNumber(num): Promise<void>
    // updates this.currentPage

async resetToFirstPage(): Promise<void>
    // force-loads page 1.
    // Intended to be called after the order of the dataset changes (like 
    // after sorting), or after the total number of items changes (like after 
    // a search).

Inheritance Chain

AppPaginator<--AbstractAppPaginator

Installation

npm i @writetome51/app-paginator

Loading

// If using TypeScript:
import { AppPaginator } from '@writetome51/app-paginator';
// If using ES5 JavaScript:
var AppPaginator = require('@writetome51/app-paginator').AppPaginator;

License

MIT