For a recent project I ran into a slight issue with the jQuery change event. It’s not an issue with jQuery, but I was quite surprised when it didn’t work as I expected. I’d set up a selection of form inputs that a user could change; once changed various calculations would be made and the values outputted to a second set of disabled input elements (demo). The inputs are disabled as they are to be calculated rather than entered manually.
I’d attached the jQuery change event to the output elements like so:
So the plan was, once an input value had been changed using the jQuery().val() method the change event would fire and it would quickly colour in and out the element (using highlightFade) to notify the user that it’s value had changed. Unfortunately the change event wasn’t firing, so I had to find another way to monitor the output elements.
What I ended up doing was using an array to hold the previous values of the input elements then checking to see if they had changed in the calculation. If changed then fire the event:
1 2 3 4 5 6 7 8 9 10 11 12 13
//Array to store the old values var oldValues =[];
//Push these values into an array which is checked on calculation
$("#valueOutput input:text").each(function(i){ var thisValue = $(this).val(); //If the old value is different to the new, change the colour if(oldValues[i]!== thisValue){
$(this).highlightFade('red'); } //Push the new value into the array
oldValues[i]= thisValue; });
It’s quite hard to explain exactly what’s happening so I’ve put together a small demo. Try changing one of the top input fields then tab (or click out) of the input element to recalculate. Is there an easier (or better) way to do this? Comment below.
Well 2011 is nearly upon us; which leaves me thinking… where did 2010 go! I hope I’m not the only one who thinks this year has gone quick! One big web application that died in 2010 was digg.com. I used to use it every day for the latest technology and funny videos, but then they changed it. The design became very blue and digg seemed to change from a simple community driven link aggregator to a, well, I’m not sure what it changed to in all honesty. So it was time to find an alternative.
Luckily for me (and all digg users) there’s already a well established alternative: reddit.com. It may not look as flashy as digg, but it makes up for it with ease of use and functionality. Need to set up a community for your web application, current technology, interest or well, just about anything really; then reddit is the place for you.
So that’s exactly what I’ve done for Mr. doobs three.js JavaScript library. I created a Threejs community that anyone can submit links to relating to three.js. Over the past few weeks I’ve been adding a couple of links a day, there really are a great selection of examples out there if you take the time to hunt then down.
So if you’ve created a cool new example using three.js or any other link relating to this excellent JavaScript library submit it here. Digg is dead. Long live reddit.com!
It’s been a few weeks now since I attended a Web Gaming event hosted by Mozilla and I’ve not yet had chance to write about one of the coolest features that was demonstrated: Speech input in forms. Now I must admit, I had no idea this was even possible; so it was quite a surprise when I saw the demonstration. With a few extra attributes added to a standard input box you can enable speech input:
It really is that simple! You may notice the “x-webkit-speech” attribute so will have guessed it currently only works in Webkit; and as far as I’m aware only in very recent versions of Google Chrome (note: “The Input Speech API will now be available by default on Chrome’s dev-channel”). The Speech API seems very new and is still a draft, so it will be a while before it’s fully adopted by other browser vendors.
A quick demonstration of the Speech API in action.
To demonstrate the speech input I’ve put together a very simple festivedemo that queries the Flickr API looking for images related to a value entered. So if you have a microphone and the dev channel of Chrome, why not give it a try. Chrome records the input of the microphone before sending it off to an external server to be processed, where a value is then sent back to the browser. At first I thought it was all processed inside the browser but I guess that’s a little to much to expect! It isn’t 100% accurate and the demo accepts Googles first guess so you may get a few strange results. The server returns multiple guesses which a user can select from, but this hasn’t been added (to my demo at least).
Since the API is very new it took a little trial and error to work out how to detect if the Speech API was available in the browser; but with a little help from Paul Irish I managed to crack it:
1 2 3 4 5
function speechcapable(){ var elem = document.createElement('input'); var support ='onwebkitspeechchange'in elem ||'speech'in elem; return support; }
This function will return true if the API is available. It’s worth noting that since it’s very new this function is likely to break in the future as the properties always seem to be changing. It works at the moment, so get thinking about what this brilliant new API can be used for! It’s a big plus for accessibility if used correctly and I can also see some cool applications in web gaming too. View the demo.
Anyone who’s read my latest blog posts will know that I’m a big fan of Mr doobs Three.js JavaScript 3D engine, so I won’t bang on about it any more than I have to. For my latest experiment I decided to mix the HTML5 File API, Three.js and a few images (demo here).
Mr Doob and a little kitten sitting in a 3D tree.
The File API allows a user to upload a file (an image in this experiment) to a web application simply by dragging it onto a designated “droparea”. Once dropped, you can manipulate the data any way you like. The API is able to handle multiple files natively, so just select all the files and drop them onto the area. No need for Flash uploaders or multiple browse boxes. Of course not all browsers support it (IE) and there are a few inconsistencies in the specification; but they will work themselves out over time.
So what does the experiment actually do? Well it allows a user to drag an image onto their browser window which is then “uploaded”; the data is then passed to a canvas element and then this data is passed to Three.js to be plotted in 3D space. The X and Z-axis is plotted in the usual manner to represent the default 2D image using particles; the fun bit comes when you add the Y-axis. This is calculated by taking an average of the RGB values (greyscale) and plotting it accordingly. When using an image of a human face it’s amazing how accurate the 3D plot looks.
Due to the amount of data involved it is recommended that you use small thumbnail images when you try the demo, as larger images equal a larger number of particles. This is an initial version so I’m going to work on a way of dealing with larger images. This will probably mean ignoring a certain number of pixels when looping through the image data. Looking forward, since it can be done with a static image I see no reason why it can’t be done with a video, but that’s a project for another day!
Update: I’ve updated the demo slightly; as Mr.doob pointed out people may have tried to drag directly onto the render area which didn’t work. So now it does :)
Anyone who’s been following the progress of the Three.js 3D JavaScript engine will know of alteredq, as he’s been helping with its development along-side Mr. doob. His latest demo using Three.js really impressed me:
A WebGL ninja! People, I think we may have just found the end of the internet.
The demo uses Three.js, WebGL and Web Workers; so that pretty much ticks every box for me. The model is from AMD’s MeshMapper which is no longer supported. I can’t say I’ve ever heard / used it before but it’s certainly on my to-do list to try out.
To view the demo see here; be warned though you will need an up to date browser that supports WebGL and Web Workers. Grab a recent version of Chrome and enable WebGL and it should work.
If you really want to push the boundaries you could try the latest Canary Build of Chrome (10.0.605.0 at time of writing) which now has an optimised version of V8, called “Crankshaft”. It uses runtime information to see which code will benefit from the most optimisation and is 2 times quicker in some tests! The Canary Build release channel of Chrome is meant for developers / early adopters who want to try out the latest features. Unlike the dev and beta release channels the Canary Build is installed independently, so it won’t overwrite your current chrome settings.
Bring on the revolution; to paraphrase a well known mobile company: The future’s bright, the future’s WebGL.
