I’ve built a couple of HTML5 (jQuery Mobile) applications that have also targeted native app stores using PhoneGap. When building these applications, it becomes clear that to get desired navigation in iOS, one must carefully consider the PhoneGap settings for url handling “OpenAllWhitelistURLsInWebView” and “ExternalHosts”. In many configurations this results in setting the “OpenAllWhitelistURLsInWebView” to “YES” and Subsequently setting a single “ExternalHost” as “*” in order to keep your application functioning within the WebView exclusively. This is great for everything except where you wish to open an external link that would break your HTML5 applications navigation (due to a lack of back button). What follows are a few tricks I have picked up to help with whitelisting. In many cases you know when you’re building your application where you’d like to have the external links open, in which case you can set these external links within your Objective-C source code letting the applicaiton know which links to open. This would look something like the following Gist (which looks to the prefix of the URL in order to open a link outside of the WebView):

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    if ((navigationType == UIWebViewNavigationTypeLinkClicked) &&
        ([[[request URL] absoluteString] hasPrefix:@"https://www.google.com"])) 
    {
      [[UIApplication sharedApplication] openURL:request.URL];
      return NO;
    }
    return YES;
}

In other cases, your application may allow for some dynamic client created content to come from the server. This can mean either a maintenance nightmare for setting up this prefixed whitelist, where you get to update the whitelist and resubmit the app to Apple everytime the list changes (icky)…. Or we can come up with a solution that works better. One way in which this can be accomplished is by looking to the suffix of the URL to find a querystring parameter that would indicate that we need to open external.

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
  if ((navigationType == UIWebViewNavigationTypeLinkClicked) && ([[url absoluteString] hasSuffix:@"?openExternal=1"] ))
  {
    [[UIApplication sharedApplication] openURL:url];
    return NO;
  
  }
  
  return YES;
}

A perhaps more robust solution, allow for the conversion of any link with target=”_blank” to open in Safari. This solution is inspired by this where you tell your iOS app to find a specified document fragment, and also tell your web application to ensure that target=”_blank” links always have such a fragment. The Obj-C code looks like this:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
  NSURL *url = [request URL];
  if ( ([url fragment] != NULL) && ([[url fragment] rangeOfString:@"openExternal=true"].location != NSNotFound) )
  {
    if ([[UIApplication sharedApplication] canOpenURL:url]) {
      [[UIApplication sharedApplication] openURL:url];
      return NO;
    }
  }
  return YES;
}

and telling the webapp to set this fragment (using jQuery) looks as follows:

/* turn all target = _blanks into whitelisted urls */
$(document).on("click", function (event) {
  if (event.target.target === "_blank" && event.target.href.indexOf("#openExternal=true") === -1) {
    event.target.href = event.target.href + "#openExternal=true";
  }
});

I dunno if this is a full fledged review or not, but I recently picked up and read the new book JavaScript Enlightenment by Cody Lindley, and I found it ranks in my list of JavaScript books I would direct others to read in their quest to JavaScript wizardry. Lindley states he writes his book first and foremost for himself, as a personal reference, which I find handy because that is exactly how I like to read JavaScript books. His approach to teaching the language might strike some as contrary to what is found in the wild - he spends plenty of time not using object literals when creating objects in order to hammer home the underlying principles of JavaScript objects - but he does also hammer home that using literal notation is preferred for its terseness and readability.

What else did I like about this book? Well I enjoyed the use of code examples, as its always good to see JavaScript in action. He also makes many great succinct notes that help make good distinctions such as “Remember: object instances created from constructor functions are just plain old objects”. Another concept that those in search of JavaScript enlightenment should find well laid out in “JavaScript Enlightenment” is how the prototype chain is traversed whilst accessing a property on an object. Along with traversing the chain, Lindley describes through an example of what not to do, how prototypes can be altered even on the Object.prototype, promptly reminding the reader that this is a “forbidden” example. Since the prototype is key in JS, the book dedicates a considerable portion to describing and outlining how it all works.

The book describes in great detail and examples many concepts that any front-end engineer should be familiar with. Things such as the Function objects instance properties and methods - you know: arguments, constructor, length, apply(), call(), toString() - including going into specific examples on how to use arguments.callee when calling a function recursively. The discussion of JavaScript scope and closures is straightforward and to the point without over complicating concepts that are sometimes hard for some developers to grasp.

Other parts of this book I would describe as desk reference material. These are items that are common and I think are generally understood by many, but in the case someone runs into a gotcha during development, they may find it useful to hit the chapters on the various objects: Array(), String(), Number(), Boolean(), as well as then utilizing String, Number, and Boolean primitives. Other desk references: Math(), null, and undefined.

I’d totally recommend this book on the same JavaScript binge handed to new developers when the get underway (things like The Good Parts, Eloquent JavaScript, JavaScript Web Applications, or any of the many many useful links to the plethora of great resources available to the modern developer). I guess this did turn into a full fledged review.

On 11 November 2012, my first patch to jQuery-UI landed in the project. It was not the world’s greatest pull request, nor was it the best code ever written (by a long shot).  But it was important. Not because I get my name on a change log somewhere, or that I will now conquer to world with my open source prowess. Its important because it is another tiny step in the massive open source snowball that wins. It wins big. The open web as we know it has spiraled out of openness and open source projects. The documentation that I turn to regularly and have contributed to is open and invites new contributors each day. There are countless open initiatives in the world these days - and by no means are these all software related - these encourage the scientist in us all to submit pull requests, change direction and assert for the greater good. If you have a passion, pursue it. That is all.

Recently I was tasked by my son’s pre-k teacher to present a paragraph that describes my occupation… in a way that 4 year olds will understand. This really put things into perspective for me, more than I thought it would. At first I think of what I might describe to my parents: “Software Engineer: I write code for web applications and databases”… No. So what is it that I do?

I was then reminded of an interview question I once had where I was asked: “How would you describe a database to your grandmother?”  These sorts of questions may seem silly to some developers, but I find them to be a great exercise. These questions help us to target and focus on what it is we really do, and how our end users or clients might perceive what someone in the software profession might be thinking. So I thought of the answer provided in that interview where I made the analogy of a jewelry box that helps to organize and sort jewelry for efficient placement and retrieval.

How does a jewelry box translate to pre kindergarten children? Well I tried to avoid an abstract analogy and simplified it by stating that I teach computers to do neat things and give us information when we ask them for it by typing or clicking the mouse…. Our children don’t care about CSS, HTML5, JavaScript, objective-C, C++, Java, Ruby, Python, C#, or if we built our app for Android, iOS, Windows Phone 8 or whatever,
they care if they can learn from and enjoy whatever it is we built.

So a fresh perspective of “how can this actually benefit someone” has been bouncing in my head lately. I’m not saying one shouldn’t try new cool tech… Still create experiments and things that push development forward, but perhaps a deeper look at what is truly needed should be a priority.

This week Microsoft released its shiny new JavaScript pre-processor - TypeScript. It represents a superset of JavaScript that is designed for large-scale application development. It utilizes concepts that most developers are comfortable with in their non JavaScript languages. Things like Classes, Modules, and Type checking.

These are all things that many people complain that JavaScript does not have built in.  With TypeScript, JavaScript does not magically gain these things. TypeScript makes these things accessible to a developer through its pre processing. Developers and JavaScript do not need TypeScript, and it is not a requirement to build large scale applications. It won’t magically make crappy programming better, but it may help catch a gotcha for someone every now and again, just as JSHint would. I for one think that it will take off rather well, especially in the ASP.Net community. I also will probably try it out in a project or two or three. I like that it looks and feels like JavaScript, which is a syntax that I am comfortable with.  That is one reason why I have not adopted CoffeeScript, it just looks so foreign to me. I suppose if I were a full time Ruby on Rails developer, CoffeeScript would feel right, but I’m not, so it doesn’t.

I’m going to end this by just showing the difference between TypeScript and JavaScript. It is subtle and that is appealing to me. See the comparisons below:

// TypeScript
class Greeter {
	greeting: string;
	constructor (message: string) {
		this.greeting = message;
	}
	greet() {
		return "Hello, " + this.greeting;
	}
}   
 
var greeter = new Greeter("world");
 
var button = document.createElement('button')
button.innerText = "Say Hello"
button.onclick = function() {
	alert(greeter.greet())
}
 
document.body.appendChild(button);

// JavaScript
var Greeter = (function () {
    function Greeter(message) {
        this.greeting = message;
    }
    Greeter.prototype.greet = function () {
        return "Hello, " + this.greeting;
    };
    return Greeter;
})();
var greeter = new Greeter("world");
var button = document.createElement('button');
button.innerText = "Say Hello";
button.onclick = function () {
    alert(greeter.greet());
};
document.body.appendChild(button);

July marked the beginning of the coding portion of the Liberated Pixel Cup which is an amazing two-part competition that involves amazing artists creating open game assets during part one (June) which developers then take to create a game based on those assets (July). I first heard about the Liberated Pixel Cup a few weeks into the second part of the competition. After a day or two of contemplating if I could get a game off the ground in time, decided to make an HTML5 game. Other than my orientation demo Catch and the node.js interpretation of the card game Wizard, I had not made (or at least published) what I would consider a graphics based, animated, HTML5 game. I decided to take this opportunity to dive in head first.
Over the last few years, I have seen quite a few HTML5 game engines come around and have taken note of many, experimented with some. The big name in the HTML5 engine space right now seems to be ImpactJS which I have yet to use, but of the ones with which I have experimented,cocos2dx-html and melonJS, I chose melonJS. I decided that to get an RPG style game with the assests provided in the competition playable in the limited development time that I had, melonJS fit that need perfectly. So now I can kill two birds with one stone, get an HTML5 game built and get more familiar with one of the HTML5 engines I have been eyeing for some time.
So I spent my evenings and weekends for the last couple weeks doing quite a bit of hacking. First I had to familiarize myself with making some tilemaps for the different world areas within the game that I wanted to create, figure out how that tied in with the melonJS framework that I was trying to learn, and create a simple story in the game which could be completed before interest is lost. Creating the tilemaps was easy, and the way in which melonJS incorporates them into the game is slick and effective. A couple things which weren’t clear from the melonJS documentation were 1) dynamically adding projectiles or arbitrary objects (such as the magic in my game) to the screen, and 2) how to get the level transitions to behave how I wanted. The first was pretty simple in the end, all I needed to do was check if my player had the magic, check direction, create & align, add it and make sure it displays on the scene:

if (me.game.STATE.weaponState === "magic_torrentacle") {
    if (this.direction === "west") {
        magic = new MagicEntity(this.pos.x - 100, this.pos.y + 30 , { image: "magic_torrentacle", spriteheight: 128, spritewidth: 128});
        magic.flipX(true);
        me.game.add(magic, this.z);
        me.game.sort();
    } else if (this.direction === "east") {
        magic = new MagicEntity(this.pos.x + 42, this.pos.y + 30, { image: "magic_torrentacle", spriteheight: 128, spritewidth: 128 });
        me.game.add(magic, this.z);
        me.game.sort();
    } else if (this.direction === "south") {
        magic = new MagicEntity(this.pos.x - 24 , this.pos.y + 100, { image: "magic_torrentacle", spriteheight: 128, spritewidth: 128 });
        me.game.add(magic, this.z);
        me.game.sort();
    } else if (this.direction === "north" ) {
        magic = new MagicEntity(this.pos.x - 24, this.pos.y - 30, { image: "magic_torrentacle", spriteheight: 128, spritewidth: 128 });
        me.game.add(magic, this.z);
        me.game.sort();
    }
}

The other major hurdle I faced was the scenes when jumping from one map to another would sometimes immediately jump to a completely different map. This seemed like a bug and was so inconsistent I nearly scrapped the whole project, but as it turns out, a few of my enemies were walking their boundaries to the point where the level transitions began, triggering a random map change as if it were the main player. So that was a quick fix (once I figured it out). I do hope to add some more fun to it as time goes on, and welcome any contributors to expanding it to whatever it becomes. So go ahead and Fork it.
I cannot thank the other contributors to the competition enough, they are a cheery bunch on IRC who have donated time and talent to a really cool open game competition.
So now you know a bit of the backstory that led up to Pixel Quest, my HTML5 entry in the 2012 Liberated Pixel Cup.

Months ago I set out to create a nodejs based app for one of our office favorite games - Wizard (the ultimate game of trump). I started the project by myself, but after I got it to the point where I thought it could really become something I enlisted the help of a friend to help contribute to really speed up the development. Things went well and we reached the point  somewhere around SXSW 2012 where it became playable and testable, though admittedly it is still in a fairly unstable state. We had privately hosted it on Bitbucket and collaborated through there, but I decided today that we are going to unleash it as a public repo on Github.  So there it is. You can create your own instance of it and test and contribute (pull requests, issues, etc) as much as you like.  If you just want to see it in action, you can view the latest stable build that I have hosted with nodejitsu currently at http://wiz.jit.su.

Recently I have been working on some mobile content for a couple of my personal projects. And since working on the front-end of these projects involves spending some quality time with developer tools, I have also been spending some quality time utilizing a few different remote debugging tools. In the last few years the remote debugging tool category of software has grown rapidly which makes deciding on the best tool, somewhat similar to finding your favorite dev tools setup in your browser of choice. Just as some folks prefer debugging their front-end with Firebug, Opera Dragonfly, or Chrome Developer Tools (WebKit Inspector), there is now a similarly robust selection for remote debugging for mobile devices.

Built by Remy Sharp, JsConsole.com is perhaps the simplest and most accessible tool for remote debugging. Simply include the remote.js file in your html,

<script src="http://jsconsole.com/remote.js?IDENTIFIER"></script>

navigate to jsconsole.com, “:listen”, and you now have access to your remote device. Works splendedly, but doesn’t have all the bells and wistles that come along with the advancing browser dev tools. I use this tool a ton for remote debugging work, especially since it works across browsers on my mobile device. Another tool that I have utilized and is quite popular due to its association with PhoneGap, is Weinre or WebKit Inspector Remote. With this you simply run a server locally that will allow you to debug remotely utilizing a set of the WebKit Inspector toolset (Google Chrome, Safari) - provided you supply a target.js script in your source. Again this is not a full set of the tools which are normally available to a Chrome Dev Tools, Firebug, Dragonfly user, but is quite adequate and useful on multiple target browsers. I rarely utilize Weinre, but many developers find it a critical part of their workflow.

Opera Dragonfly has a great remote debugging experience baked into their tools. One simply tells Opera Desktop to initiate a remote listening session, then Opera Mobile “opera:debug”, and you can inspect your remote page in Dragonfly. Honestly, I have limited experience here, because I rarely utilize Dragonfly, even though the tools are quite robust.

So what is my go to remote debugging tool today? Chrome. I am most comfortable with the Chrome Dev Tools in all my other debugging for a number of reasons including the continuous insertion of handy new features. So once I upgraded my phone to Android 4 (Ice Cream Sandwich) - which is required to utilize Chrome For Android - I have been happily utilizing the full suite of Developer Tools in Chrome to inspect my mobile app on my Android device. Again, the best solution for me because I can utilize the same toolset for desktop or mobile debugging. Its pretty simple to setup, just get your Android device set up for usb debugging in both the Android settings and Chrome settings, then (via the Android SDK) setup a debug bridge that will forward your console to a port of your choosing allowing you to open localhost:9222 which shows all your tabs open on your phone, ready for inspection. Start listening on that port using a script like this in your terminal:

adb forward tcp:9222 localabstract:chrome_devtools_remote

Rather than go through my terminal command history to find the command and possibly change the port, I aliased the command in my .bashrc file so anytime I hook up my phone I can type cremote 9222 in the terminal and inspect away

function cremote() {
    adb forward tcp:$@ localabstract:chrome_devtools_remote
}

From there its on to your browser to find and inspect away to your hearts content. This remote debugging space is growing quickly, the upcoming version of many toolset have this capability built in directly, things like jsBin (v3), jsfiddle, Firefox dev tools, Adobe Shadow, Trigger.io’s remote inspector, and many others I’m sure are all available, or will be available to utilize as a remote debugger. So the developer wins in the end with a host of choices to choose from so they can find that which fits their needs and workflow.

The Mozilla Dev Derby is a pretty cool thing. Developers from around the world can openly add any demo to the site, and if their demo lines up with the prescribed derby for the month, they are automatically entered to win a prize (t-shirt, cool bag, android device). I decided I would enter again for the January 2012 derby based on Orientation. I made two demos.

catch

The first one called “Catch” which you are attempting to catch a randomly generated ball in the shortest amount of time possible. I have personally found it incredibly addicting to get the perfect game, or at least my best attempt at it and I even wrote the source code. What I learned in developing this app was a couple of things. One, there isn’t a ton of documentation on the web about the DeviceOrientationEvent. Two, its pretty straightforward to detect the orientation and utilize it to move an object. Here is the basic of my app:

 /*orientation stuffs*/
var initOrientation = function() {
    var count = 0, gam = 0, bet = 0;
    if (window.DeviceOrientationEvent) {
        window.addEventListener("deviceorientation", function(e) {
            //gamma = left to right
            //beta = front back
            //alpha = compass dir
            count = count + 1;
            gam += e.gamma;
            bet += e.beta;

            if (count === 0 || count % 10 === 0) {
                orientationYo(gam, bet);
                gam = 0;
                bet = 0;
            }
        }, false);
    }
};

//handle orientation
var orientationYo = function(ltr, ftb) {
    coor.x = coor.x + ltr;
    coor.y = coor.y + ftb;
    if (!gameState.victory && gameState.playing) {
        tgt.move(coor);   
    }
};

so that handles the detection of the orientation event, next I simply added the move call to my target (tgt) which looks like this:

var tgt = {
    isDrawing: false,
    collided: false,
    start: function(coordinates) {
        this.drawIt(coordinates);
        this.isDrawing = true;
    },
    drawIt: function (coordinates) {
        ctx.clearRect(0, 0, canvasWidth, canvasHeight);
        ctx.fillStyle = b2_color;
        ctx.beginPath();
        ctx.arc(coordinates.x, coordinates.y, 25, 0, Math.PI * 2, true);
        ctx.fill();
    },
    move: function(coordinates) {
        if (this.isDrawing) {
          this.checkBounds(coordinates);
          this.drawIt(coordinates);
        }
    },
    finish: function(coordinates) {
        this.isDrawing = false;
        ctx.lineTo(coordinates.x, coordinates.y);
        ctx.stroke();
        ctx.closePath();                
    },
    checkBounds: function(coordinates) {
         if (coordinates.y > bound.y2) {
            coordinates.y = bound.y2;
          } else if (coordinates.y < bound.y1) {
            coordinates.y = bound.y1;
          } else if (coordinates.x > bound.x2) {
            coordinates.x = bound.x2;
          } else if (coordinates.x < bound.x1) {
            coordinates.x = bound.x1;
          }
    }
};

collision detection is handled by my randomly placed bouncing ball, which detects when the target ball moves into its path:

checkObjectCollisions: function() {
    var imgData = ctx.getImageData(this.position.x + this.velocity.x1, this.position.y + this.velocity.x2, r, r),
        pix = imgData.data;
    for (i = 0, n = pix.length; i < n; i += 4) {
        if (pix[i] !== 0) {
            this.collided = true;
            if (Math.abs(this.velocity.x1) > Math.abs(this.velocity.x2)){
                this.velocity.x1 = -this.velocity.x1 * drag;
            } else {
                this.velocity.x2 = -this.velocity.x2 * drag;
            }
            break;
        } else {
            this.collided = false;
        }
    }
}

I am pretty happy with the game, its clean and works nicely. You can check it out here

compass

The other is a simple web compass where I utilize the DeviceOrientationEvent to get the cardinal direction your phone or device is facing. There are two cool (in my opinion) things that happened here. One is that to me it seems the device orientation event as defined states that the DeviceOrientationEvent.alpha ranges from 0 to 360 which to me is a 361 degree circle. The second is that I was able to utilize the offline caching capabilities of the modern web to make the compass available to a device event when not connected to the internet. This is done in minimal lines of code. The HTML and JavaScript are as follows:

<!-- This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this file,
You can obtain one at http://mozilla.org/MPL/2.0/.  -->

<!DOCTYPE html>
<html manifest="compass.appcache">
<head>
<meta charset=utf-8 />
<title>Cardinal Direction Compass</title>
<style>
  .pointer {
    height: 0;
    width: 0;
    border-left: 3em solid transparent;
    border-right: 3em solid transparent;
    border-bottom: 12em solid black;
    margin: -10px 0 0 -40px;
    top: 40%;
    left: 50%;
    position: absolute;
  }
  .n {
    top: 20%;
    left:50%;
    position:absolute;
    font:8em Helvetica;
    margin: 0 0 0 -40px;
  }
  </style>
  <script src="js/jquery.js"></script>
</head>
<body>
  <div class="n">N<br><br><br><br>S</div>
  <div class="pointer"></div>
<script>
        $(document).ready(function() {

          var rotate = function (deg) {  
              $(".n").css({ "-moz-transform": "rotate(0deg)"});
              $(".n").css({ "-moz-transform": "rotate(" + deg + "deg)"});

              $(".n").css({ "-o-transform": "rotate(0deg)"});
              $(".n").css({ "-o-transform": "rotate(" + deg + "deg)"});

              $(".n").css({ "-ms-transform": "rotate(0deg)"});
              $(".n").css({ "-ms-transform": "rotate(" + deg + "deg)"});

              $(".n").css({ "-webkit-transform": "rotate(0deg)"});
              $(".n").css({ "-webkit-transform": "rotate(" + deg + "deg)"});

              $(".n").css({ "transform": "rotate(0deg)"});
              $(".n").css({ "transform": "rotate(" + deg + "deg)"});
          };
          if (window.DeviceOrientationEvent) {
            window.addEventListener("deviceorientation", function (e) {
              rotate(360 - e.alpha);
            }, false);
          }

        });
        </script>
  </body>
</html>

The final point I’d like to make is that due to what I thought was minimal documentation, I participated in a Mozilla Doc Sprint last weekend to update the Documentation surrounding the DeviceOrientationEvent. Doing my part in the web development community was both rewarding and a learning experience. I encourage anyone to try it out as well.