Last time we discussed the Fetch API in general, taking a look at how it differed from the XMLHttpRequest API, and some of its advantages. Today, we're going to take a look at a little library that you can include in your projects today that offers you localStorage caching for the Fetch API.

Long ago, we briefly brushed upon the topic of what has made jQuery such a valuable part of the web developer's toolset for such a long time - namely, a cleaner interface for interacting with the DOM, and the $.ajax abstraction over XMLHttpRequest.

You've built the web application of the century, and the users have rightly flooded to it. Cat pictures for everyone!

After long, grueling months (years? or does it only feel like years?), your web application nears completion. It is tightly coded, well documented, works across all modern browsers, and is well received by your beta testers. It's nearly time to go live, and a smile of pure relief plays upon your lips... and freezes into a rictus grin when your client turns to you, and asks, "so, hey, can we speed up the dynamic cat pic loading? Especially when I close the browser and come back to it later. I think that's really key to the whole application."

In a hurry? You can now use our HUp jquery plugin to read files in a chunked fashion as data URLs. Hooray!

Way back when I brought up the topic of promises (particularly, jQuery Deferred), and I promised we would come back to the topic someday.

Here's the situation: You've got a select. Maybe a whole bunch of selects, with a ton of options each (metric ton - let's keep our imaginary hyperbolic units straight here); and these are meant to be complex interactive elements, with options made visible or not as some programmatic condition dictates.

It's a pleasure to be able to interact with files in the browser at long last, isn't it? Reading files in without needing to bounce them against the server first opens up a lot of possibilities - and getting progress from a chunked ajax upload is miles away from the indeterminate form uploads of days past.

A big part of what makes jQuery a regular part of so many web projects is the clean interface it offers us for a number of sometimes messy built-in aspects of javascript. The most obvious is the DOM interface; and in second place, jquery ajax and its various shorthand methods. Abstracting away the difference between ActiveXObject and XMLHttpRequest is one of the most obvious benefits - but even if you don't need to worry about supporting old versions of IE, you might well enjoy the clean, object-based, promise-returning interface that jquery ajax offers.

Inevitably, people want their files on the Internet. If your project is about cute cats, someone will task you with allowing users to upload photos of their cats, videos of their cats, long rambling audio clips in which they attempt to convince their cat to stop attacking the microphone, etcetera. If your project is about the nature and proclivities of mold, someone, somewhere will want to share detailed photographic evidence of their mold problem. The need to upload files is a given.