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jQuery Mobile - Full Height content area

I was working on integrating jQuery Mobile stuff into fingerpoken and needed a way to make the content area of pages full-screen. By 'full screen' I mean still showing the header and footer, but otherwise the content needs to fill the rest.

I couldn't find an easy way to do this while googling, and even the jQuery Mobile demos didn't do it.

So here's a demo of what I came up with here: fullheight jQuery Mobile demo Javascript:

  var fixgeometry = function() {
    /* Some orientation changes leave the scroll position at something
     * that isn't 0,0. This is annoying for user experience. */
    scroll(0, 0);

    /* Calculate the geometry that our content area should take */
    var header = $(".header:visible");
    var footer = $(".footer:visible");
    var content = $(".content:visible");
    var viewport_height = $(window).height();
    
    var content_height = viewport_height - header.outerHeight() - footer.outerHeight();
    
    /* Trim margin/border/padding height */
    content_height -= (content.outerHeight() - content.height());
    content.height(content_height);
  }; /* fixgeometry */

  $(document).ready(function() {
    $(window).bind("orientationchange resize pageshow", fixgeometry);
  });

Server-side javascript.

Tonight I played with Mozilla Rhino and a few other toys.

Serving webpages dynamically with javascript on the server-side just feels strange. Ignoring the strange sensation in my brain, the concept of server-side javascript is a good one.

Client-side web scripting is javascript. Server-side is typically not. This means input validation and other common code has to be written in two different languages. This leads to bugs. One language on both ends lets you share lots of code trivially. Neat.

javascript: the 'top' object.

My jquery puffer demo wasn't working in IE. This was the error:

Line 25 is:

  top = pos[1];

Turns out 'top' is one of those magically populated objects. In Firefox, you are allowed to assign to top and hence the demo works. In IE, it tells you that assignment is not implemented for that particular object.

In IE, alerting 'top' will show '[object]'. In Firefox, alerting 'top' will show '[object Window]'

If I change my code to use 'top_pos' instead of 'top', the demo works now.

Firefox URL Editor extension ready.

Last week, I posted about a new firefox extension I was working on that would let you edit the contents of the urlbar more easily. Well, I have good news. It's alive.

The current incarnation is very basic, but I have some ideas for how to extend it in the future. I won't go into that now.

This extension adds a menu item to the context menu in the url bar labeled 'Edit URL'. This will bring up a dialog box with a table of key-value pairs listed. You can edit, add, or delete entries. Clicking 'OK' will modify the url based on your changes. It automatically unescapes values and re-escapes them later.

Download urledit.xpi

Firefox tab search extension

I'm tired of searching through my piles of open tabs in firefox using only my eyes. Make the computer do the hard work! To fix this, I wrote an extension that will let you quickly search (unobtrusively!) your open tabs. Super useful. Check out the project page:

View the screencast demo

Visit the firefox-tabsearch project page

Query parsing in JavaScript

For pimp, I want to be able to search a specific column, say, artist, without needing multiple fields for searching. The ability to specify more advanced searches than simple keywords is quite useful. How do we leverage this on the client and turn a search query into a set of key-value pairs?

I must confess I was hesitant to put this kind of logic into Javascript instead of Python. Furthermore, it makes me feel a little uneasy using /foo/ in anything other than Perl. Nonetheless, doing this in Javascript was simple and it's still fast (as it should be).

The particular type of query I want to parse come in the following (hopefully intuitive) formats:

  • foo
  • artist:Eminem
  • album:"Across a Wire"
  • artist:"Counting Crows" album:august
The following code does this for me. The parse_query function will return a dictionary of query terms. Values are lists.

Here's an example:

Query
rain baltimore artist:"Counting Crows" album:august
Results of parse_query
    { "artist": ["Counting Crows"],
      "album": ["august"],
      "any": ["rain", "baltimore"],
    }
  
I take the dictionary returned and pass it to jQuery's $.post function to execute an AJAX (I hate that term, it's such a misnomer these days) request. Here's the code:
query_re = /(?:"([^"]+)")|(?:\b((?:[a-z:A-Z_-]|(?:"([^"]+)"))+))/gi,

function parse_query(string) {
  dict = {}
  while (m = query_re.exec(string)) {
    val = (m[1] || m[2]).split(":",2)
    if (val[1]) { key = val[0]; val = val[1]; }
    else { key = "any"; val = val[0]; }

    val = val.replace(/"/g,"");

    dict[key] = dict[key] || [];
    // the following should be .append(val) but 
    // I don't think javascript lists have them
    dict[key][dict[key].length] = val;
  }

  return dict;
}

jQuery puffer

The Interface elements plugin for jQuery is super slick. It has a puffer function I want to use. However, the act of 'puffing' makes the element disappear. I want to clone the element and puff the cloned version.
  function magicpuff() {
    $("img").mousedown(function() {
      pos = findPos(this)
      left = pos[0];
      top = pos[1];

      puffer = this.cloneNode(true);
      puffer.style.left = left + "px";
      puffer.style.top = top + "px";
      puffer.style.position = "absolute";
      $(document.body).append(puffer);
      $(puffer).Puff(1000, function() { $(puffer).remove() });

      return false;
    })
  }
  $(document).ready(magicpuff);
This code will duplicate the image clicked placing it directly on top of the old element. It then puffs the new element and removes it when the puff has completed. Simple enough.

What good is code without a fun little demo? View the puffer demo

I should note that it seems that the remove portion doesn't always remove the cloned object. This is especially noticable (though, not visually) when you activate puffing on more than one image at a time. You need somewhat fast hands to do this. Firefox's DOM inspector will show you the additional elements parented by the body tag.

This depends on findPos available from quirksmode, jQuery, and the forementioned Interface plugin.

jQuery autofill version 2

This post marks 4 in one day. Whew!

Resig and I were bouncing ideas around after I made the form filler, and we came up with something that fits very nicely into the jQuery api (in the form of something very pluggable).

You'll need the following code that will extend jQuery's functionality. Basically, it adds 'saveAsCookie' and 'loadAsCookie' function calls to $() objects.

$.fn.saveAsCookie = function(n,t){
   return this.each(function(){
     createCookie( (n || '') + (this.name || this.id), this.value, t );
   });
 };

$.fn.loadAsCookie = function(n){
  return this.each(function(){
    this.value = readCookie( (n || '') + (this.name || this.id) );
  });
};
You can safely put that code somewhere and load it anywhere you need autofill. Reusable code is awesome.

Now, we don't want to cache *all* input elements, becuase only some contain user-input and only some need to be saved. For this, I put the class 'cookieme' on all input elements I wanted to save.

 $(document).ready(function(){
   $("form#comments_form").submit(function(){
     $("input.cookieme",this).saveAsCookie("formdata");
   })
   .find("input.cookieme").loadAsCookie("formdata");
 });
The arguments to 'saveAsCookie' and 'loadAsCookie' are namespace prefixes. This way, you can avoid namespace collisions with other cookies. All of my autofill cookies will be prefixed with 'formdata' and suffixed with the element name or id attribute.

So, we squished the code down to 6 lines, 4 of which are actually meaningful.

jQuery++

jQuery+cookies = trivially simple form autofill

It's always nice when websites you commonly visit remember things about you, or atleast give the perception that they remember things about you.

The Pyblosxom comment plugin doesn't autofill the form. That's too bad. I don't really want to dig into the python code to do any cookie-setting on submission, becuase I have never looked at the code and thusly am unfamiliar with the effort required for such a change. Luckily, we can use javascript to store data in cookies too!

I love jQuery, so that's what I'll use for this little hack. On the comments page, I add the following javascript:

   var uname = "u.name";
   var uemail = "u.email";
   var usite = "u.site";

   function saveCommentInformation() {
      // Save user information from the form!
      createCookie(uname, $("input[@name='author']").val());
      createCookie(uemail, $("input[@name='email']").val());
      createCookie(usite, $("input[@name='url']").val());
   }

   function initCommentForm() {
      // Autofill user information if available
      $("input[@name='author']").val(readCookie(uname));
      $("input[@name='email']").val(readCookie(uemail));
      $("input[@name='url']").val(readCookie(usite));

      // Save comment information when form is submitted
      $("form[@name='comments_form']").submit(saveCommentInformation);
   }

   $(document).ready(initCommentForm);
That's all we need. Whenever someone submits, we will store useful information in a cookie. Whenever that person comes back, we'll pull the data out of the cookie and put it back in the form. User Experience is happier, atleast as far as I am concerned (as a user).

If you are wondering about the 'readCookie' and 'createCookie' functions, you can find them on quirksmode.org:

http://www.quirksmode.org/js/cookies.html

Update: Check out this followup post that implements this in a more jquery-like way.

The CSH Bawls Programming Competition

Yesterday, I participated in a 12-hour coding-binge competition. It started at 7pm Friday night and ran until 7am Saturday morning. It was fueled by Computer Science House and Bawls, both sponsors of the event. Needless to say, I haven't gotten much sleep today.

The competition website is here. Go there if you want to view this year's objectives.

The Dream Team consisted of John Resig, Darrin Mann, Matt Bruce, and myself. Darrin, Resig, and I are all quite proficient at web development, so we decided this year we would represent ourselves as "Team JavaScript" - and do everything possible in javascript. Bruce is not a programmer, but I enlisted his graphical art skills because I figured with our team doing some web-based project, we definitely needed an artist.

After reviewing all the objectives, we came up with a significant modification upon the Sudoku objective. The sudoku objective was a problem that lacked much room for innovation, so we went further and instead of solving Sudoku, wrote a web-based version of an extremely popular game in Second Life. The contest organizer approved of our new objective, so we did just that.

Resig worked on game logic, I worked on chat features, Darrin worked on scoring and game generation, and Bruce worked on the interface graphics. Becuase our tasks were all mostly unrelated, we could develop them independently. Most of the game was completed in about 6 hours, and the remainder of the time was spent fixing bugs, refactoring, and some minor redesign.

The backends were minimal. The chat backend was only 70 lines of perl, and the score backend was 9 lines of /bin/sh. Everything else was handled in the browser. We leveraged Resig's jQuery to make development faster. Development went extremely smooth, a testament to the "Dream Team"-nature of our team, perhaps? ;)

The game worked by presenting everyone with the same game - so you can compete for the highest score. You could also chat during and between games, if you wanted to.

A screenshot can be found here. At the end of the competition, we only had one known bug left. That bug didn't affect gameplay, and we were all tired, so it didn't get fixed. There were a few other issues that remained unresolved that may or may not be related to our code. Firefox was having issues with various things we were doing, and we couldn't tell if it was our fault or not.

Despite the fact that I probably shouldn't have attended the competition due to scholastic time constraints, I was glad I went. We had a blast writing the game.

We may get some time in the near future to improve the codebase and put it up online so anyone can play. There are quite a few important features that need to be added before it'll be useful as a public game.