sp-dev-fx-webparts/samples/react-offline-first

page_type	products	languages	extensions
sample	office-sp	javascript typescript	contentType technologies platforms createdDate samples SharePoint Framework react 3/1/2018 12:00:00 AM

Offline First using LocalForage, Whatwg-Fetch, ES6-Promise

Summary

Sample Web part that demonstrates how to use offline storage in a way that is more offline first.

This web part would not be possible without the great tools provided, please read the documentation for

• LocalForage
• ES6-Promise
• Whatwg-Fetch

Used SharePoint Framework Version

Applies to

• SharePoint Framework Developer Preview
• Office 365 developer tenant

Solution

Solution	Author(s)
react-offline-first	Austin Breslin

Version history

Version	Date	Comments
0.0.1	17/Feb/18	Got the HTTP Requests to work.
0.0.2	17/Feb/18	Separated interfaces into their own files.
0.0.3	18/Feb/18	Updated JSDocs, and and created readme.

Disclaimer

THIS CODE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.

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Minimal Path to Awesome

• Clone this repo
• In the command line run:
  • npm install
  • tsd install
  • gulp serve
  • Open the workbench on your Office 365 Developer tenant
  • Test out the web part

Features

This web part demonstrates using the OfflineFirstHTTPService how to do offline first HTTP Requests.

HTTP Get requests are first retrieved from an offline storage system. Either localStorage, IndexedDB, WebSQL or SessionStorage, but maybe not in that order. Then the live request is using fetch, then stored locally, errors are placed into a queue for when available.

HTTP Posts/Updates/Deletes are executed differently to GET requests, they always make a HTTP request using fetch, but on failure are added to the queue.

The Queue system collects all failed HTTP Requests and when the user is online will try to make the requests again, all requests are async so will not cause any blocking for the user.

This Web Part illustrates the following concepts on top of the SharePoint Framework:

• Using offline first techniques, store locally, retrieve locally before making HTTP requests.
• Async looping, can be found in the Queue System.
• Performance techniques for browsers, async looping does not block render, using local storage first reduces the time to draw the initial page load.