Articles in the ‘JavaScript’ Category

Sketchnotes from #LWS3D – A 50-line WebGL app

After a summer break, London Web Standards was back with an evening of WebGL with Ilmari Heikkenen from Google and a short demo from Carlos Ulloa of HelloEnjoy. Sketchnotes are below

Carlos Ulloa of Brighton-based HelloEnjoy showed off two demos that he made using Three.js and WebGL. The first was HelloRacer, an interactive look at the 2010 Ferrari F1 car that you can even drive and do handbrake turns in. The second demo got it premiere at LWS, an interactive music video for Ellie Goulding’s “Lights”. Honestly, it was extremely cool, on a Ro.me “3 dreams of black” scale. It’ll appear at the linked URL in the next week or so. There’s a great Q&A session on the London Web Standards blog of the event for more detail on how they did it.

Ilmari Heikkenen showed the gathered crowd how to make a basic WebGL app using Three.js in about 50 lines. He showed off all of the components that you need: a renderer, scene, camera, mesh and lights (and shadows). He went into more depth about vertex shaders and fragment shaders, the GPU effects that make everything look a lot more real.

Ilmari gave examples of a few uses, including games, 3D bar charts and scatter graphs. He then started animating all of these, including a 10,000 point scattergraph that moved in real-time. Finally, he demonstrated a loader for Collada meshes (supported by Maya) and brought in a monster that with a few lines of code started walking around the screen.

Overall, it was a great introduction to the subject, one worth a lot more of your time.

Ilmari’s slides can be found on his blog.

Tips and Problems when Enhancing SharePoint with JavaScript

If you’ve developed for Microsoft’s SharePoint before (I’m talking about 2007 here, but this applies to WSS2 and 2010 as well) , then you’ll know that you can reach the limits of it’s functionality very quickly. This is a big problem if you’re making a zero-code solution, i.e. you have no access to Visual Studio and can’t create web parts. This is more common than you’d think, especially in large organisations that use SharePoint extensively. For this, the only choice is to use SharePoint Designer 2007 (SPD), but it’s not pleasant because, frankly, SPD sucks. I’ve not found a program that crashes as much as SPD, or that performs so poorly when presented with the most basic tasks. If you make a page that is too complex, has too many web parts, large data sources or lots of conditionals, connections and filters, it can take anywhere up to 20 minutes to perform a single action.

SharePoint crash

Very quickly, you have to start looking at alternatives to complex data views. These days, the go-to technology is JavaScript, which is very powerful and can allow developers to access almost every SharePoint function through web services. However, this functionality comes at the cost of accessibility. So, the first piece of advice: if you can avoid using JavaScript, do so because otherwise the site won’t be accessible. See these links for why accessibility is a good thing.

Unfortunately, SharePoint is so limited that often a JavaScript is the only way to add functionality in or to correct formatting. In this case, use of simple SPD functions and <noscript> tags can keep your content accessible, allowing you to progressively enhance the user’s experience on top.

The final hurdle to cross before you can create great JavaScript-based interfaces in SharePoint is IE.

Internet Explorer, especially IE6, has appalling developer tools for JavaScript debugging. There’s no console, inspector, breakpoint facility, no nothing. It’s almost impossible to debug your problems because they all manifest themselves as runtime errors on some arbitrary line on the page.

The best way that you can debug JavaScript in IE, is with Google Chrome. It doesn’t sound right, but I promise it’s the easiest way to make your code work. Both Chrome’s Web Inspector and Firefox’s Firebug work very well with SharePoint, though my personal preference is for Chrome as it works better with Windows’ NTLM authentication system (it doesn’t ask you for your login details, just takes them from Windows). They allow you to check and validate your code so that it works well and runs as expected. You should be able to achieve this in half the time that you would if you were just developing for IE, using alerts to work out what’s going wrong.

There’s another benefit for working this way around: your code will work on standards-compliant browsers, and any that come along in the future. This is always a good thing as you don’t know when the organisation will roll out IE8/9 to its users, nor can you always guarantee that a user will be using a IE. It’s important that sites are ready for these changes and best-practice development is maintained.

In summary, if you have to use JavaScript, ensure the page content will work without it. If you are doing any major development work, do it in Chrome and reap the benefits of its debugger, then make it work in IE.

The Limitations of WebSQL and Offline apps

Web applications are the next big thing in the web. Being able to take web sites and make them run alongside native apps, having them work offline and perform just as well as their native counterparts is the next step along the road. As usual, with all new technology, there are some limitations.

There are three pieces of technology that are combined to make a web app: app caching, local storage and a web database technology.
App caching tells browsers what files to store offline and retrieve from disk. These are permanently stored until new instructions are received, unlike traditional caching which works until the cache is full, then starts removing files.

Limitation 1
In iOS 4.3, app caching for offline web apps is broken and does not work.

Local storage is for key/value pairs of information. It’s for simple things like settings and values that need to be retrieved quickly. It’s been called “cookies on crack” before, but it’s really just a very fast dictionary for simple data.

Limitation 2
Depending on your browser, localStorage will keep 5-10MB of data, the equivalent of 200,000-500,000 characters. If all you want to do is store small serialised JSON objects that aren’t related, use this.

Web databases are client-side data storage for larger amounts of more complex data. Whilst you can make web apps with just app caching and local storage, it’s not going to be very interactive, or the data may be unstructured, or there will be lots of Ajax calls to fetch data. Web databases are where this technology gets a bit dodgy.

Originally, there was Google Gears, a plug-in which brought a SQLite database to help web apps run offline. This was then standardised into the WebSQL module and developed as a SQL database available through JavaScript. Google, Apple and Opera all implemented it and it can be found in iOS and Android devices today.

Limitation 3
Chrome has a hard 5MB database size limit – you will need to use a chrome web app to remove this limit.
Limitation 4
Chrome doesn’t support OUTER JOIN or RIGHT JOIN statements.
Limitation 5
Debugging is very difficult with large amounts of data as the web inspector isn’t efficient at displaying a thousand rows (and will crash with around 20,000 rows, around 2MB of data).
Limitation 6
Version numbers are not taken into account. Don’t bother with them.
Limitation 7
All calls are asynchronous – if you rely on results at a certain time, be prepared to write a lot of callback functions. Your code can get messy very quickly.
Limitation 8
Performance is sluggish if you don’t batch up statements into transactions.

Even better still, WebSQL is no longer in development, so these problems will remain. Microsoft and Mozilla said they didn’t like it and wanted to used a different technology: IndexedDB.

IndexedDB is on it’s way, but not mature enough yet to be used, nor is it implemented in any of the mobile browsers.

Advice
For offline apps, you’re better sticking with WebSQL until IndexedDB matures.

Hopefully, some kind developer will come along and write a technology-agnostic wrapper, maybe that person will be you, the reader of this article. If you’re thinking about it, let me know :-)

Javascript Fun at London Web Standards #lwsfun

Last night was London Web Standards‘ April 2011 event, Fun with JavaScript. Speakers Rob Hawkes of Mozilla and Seb Lee-Delisle of Plug-in Media came to talk about all the fun stuff you can do with JavaScript, canvas, and HTML5. Sketchnotes for both talks are below.

We were also joined by a man showing us a quick look at Dreamweaver CS5.5 with it’s new HTML5 features. Unfortunately, the software had a few bugs which showed up in the talk, and after being burned by the very expensive adobe software for years, the crowd didn’t take to the UI very well, which wasn’t helped by a low-res projector. Still, it looks like a big improvement over the old version, but I’ll still use Coda when on my Mac.

Rob Hawkes: multiplayer gaming in HTML5

Sketchnotes of Rob Hawkes' talk Multiplayer Gaming with HTML5

Sketchnotes of Rob Hawkes' talk Multiplayer Gaming with HTML5

Rob is a canvas and animation guru. He’s not far out of uni and has a book out this month! He gave a new talk on multiplayer gaming, and how it was possible in HTML5.

Basically: Canvas + Websockets + a server (rob recommended Node.js) = multiplayer gaming on the web.

Rob didn’t go into much detail as to how to do all this, just talked us through the principles of what you should be doing, what you should avoid, how to prevent cheating and simple tricks to improve performance.

At the end, Rob proposed a HTML5 gaming knowledge repository, a community wiki and tutorial site, so that it’s easier for people to learn. Someone at the event will take him up on the offer, so look forward to more things soon!

Rob has a book on Foundation HTML5 Canvas: Gaming and Entertainment for pre-order on Amazon.co.uk

Seb Lee-Delisle: Fun with JavaScript

Sketchnotes for Creative JS visual effects – Seb Lee-Delisle

Sketchnotes for Creative JS visual effects – Seb Lee-Delisle

Seb is a flash guy, but also a JavaScript guy and a graphics guy. He’s so multi-talented that he doesn’t know what exactly he does any more.

Seb has won two BAFTAs (thanks for correcting me Seb!) for some of his BBC kids web sites. He personally runs a javascript graphics workshop and took us through a few things that we’d do if we went on it.

He started with particles, showing us how to do basic (pseudo) physics in canvas and JavaScript. He then broke out his large array of particle demos, showing how complex effects can be produced with very simple code.

Seb then talked about performance, and how bad canvas is at the moment. DOM elements with hardware acceleration is easily twice as fast as canvas, especially on the iPad. The iPad’s saving grace is its touch screen, which can take 11 touch points (just in case we grow an extra finger). Seb created a simple asteroids game using touch events for input.

Seb finally talked about 3D and how using libraries was a great way to go from 2d to 3D very simply. He recommended Unity as a game engine and framework of choice, and they’re building HTML5 renderers on top of their regular OpenGL and DirectX methods. Exciting stuff indeed.