kuwamoto.org

For the last several months, Mike and I have been working on a new project, which is nearing closed beta. That means we need to start battening down the hatches, and today was the day to start tackling client-side JavaScript performance.

I’ve actually done quite a bit of performance work in my life, but not with JavaScript, so I though I’d take some notes along the way.

Firebug is your friend

In my mind, there are really three ways to a significant dent in performance:

1. Find bad algorithms and replace them with fast ones
2. Find code that doesn’t actually have to be called and skip it.
3. Optimize the code that gets called most often

And you really can’t do any of the three without a profiler. You might think you know what the problem is, but you won’t know until you profile it. In my case, I started out thinking that I had event listeners hanging around that weren’t letting go of their events, but the profiler (in this case, Firebug) told me I was completely wrong.

To get started profiling in Firebug, go to the console tab, press the ‘profile’ button, do some stuff, and hit the ‘profile’ button again. That’s it.

You’ll then be presented with data that looks like this:

For my money, the two most important columns are ‘own time’ and ‘time’. ‘time’ is the total time spent in a function including any functions that are called by that function, and ‘own time’ is the same thing minus the time taken up by other functions.

Problem: $$(‘.class’) can be SLOW!

I created a test where I did the same UI gesture 8 times, and this is what I discovered. Looking at ‘own time’ told me that most of my time was going to DOM traversal via the $$ function.

Looking at ‘time’ told me that the methods responsible for calling $$ were all central functions that were called in many places throughout my code, so it was worth making them as efficient as possible before figuring out whether there was a way to avoid calling some of them altogether.

Phase 1 — replacing traversals of the entire DOM tree (via $$) with smaller traversals

Roughly speaking, this corresponds to strategy (3).

Along the way, I tried all sorts of other optimizations, but none of them yielded much benefit. Now that I was reaching the point of diminishing returns, it was time to see if there were chunks of code I could safely skip.

Phase 2 — skipping handler functions when possible

I knew that there was almost certainly code I was running that could be skipped (strategy 2). Why?

I find that when writing UI code, it is often easier to use brute force to make sure that everything is working consistently. For example, if an AJAX call updates a certain part of the screen, it is often easier to blow away all event handlers from everything and re-add them where needed, rather than just patching up event handlers for the portion of the screen that was updating.

My rationale is that you can always fix this at the end. And well, it was now time to pay the piper.

My test case involved doing the same UI gesture 8 times. And most of the time was going to the following functions:


add_panel_handlers_if_needed(): 8 times
add_content_handlers(): 16 times
add_panel_handlers(): 8 times
actually_do_drag_cleanup(): 8 times
remove_content_handlers(): 24 times
fix_detail_handlers(): 8 times
handle_click(): 8 times
fix_toggle_rte_handlers(): 8 times
add_drag_handlers_and_start(): 8 times
add_insert_handlers(): 8 times


You can see that some functions are being called 8 times and some were being called 24 times. As it turns out, this was just due to programmer laziness. By adding a few checks, some of those redundant calls could be safely avoided.

The other thing that was causing extra work is that only certain interactions caused screen updates that needed event handlers to be reattached. By writing some code to check for that, I was able to avoid many of these calls altogether.

(P.S. there is some small part of my brain that tells me that instead of manually worrying about these event handlers, I should just bite the bullet and switch to JQuery. But I’m not there yet.)

Summary

So, what’s the moral? First off, doing $$(‘.class’) is slow. Second, large performance boosts usually come from a combination of skipping code that doesn’t have to run and optimizing the code that does. This was no exception.

One more thing. I just have to say that Firebug is amazing. I expected it to have trouble giving useful timings in the face of inconsistent UI gestures and garbage collection, but it did the “right thing”, which many desktop profilers don’t manage to do. If I had one wish, I wish I could get it to bundle up calls from specified library files and allocate the time spent in them to the calling function.

Ok. Back to more optimizing.

I found a number of issues with the pluralizing code I posted the other day, and I felt compelled to fix it. While I was at it, I ported the code to ActionScript 3 and then back to Ruby, so you can use the pluralizer in your Flex or RoR apps.

BTW, for those of you who love language and know regular expressions (this means you, lori and nj!), please help me spot any problems with these rules.

The reason it was important for me to get these pluralization rules rights is that I am using these for human-readable strings. In my project, users get to name things however they want and it is nice to be able to pluralize (or singularize) these words when communicating with the user.

(As a side note, I think the Ruby on Rails idea of auto-pluralizing table names to be a bit bizarre. I like having magic frameworks that do all the work for me, but I want my frameworks to have predictable behavior!! I mean… how bad would it be if the table that holds the “person” object was called “person” instead of “people”?)

Thanks again to the Rails team for getting this ball rolling, and to Paul Osman for the original PHP version of this code.

On to the code. All code below is covered under the MIT license.

PHP:

// Thanks to http://www.eval.ca/articles/php-pluralize (MIT license)
//           http://dev.rubyonrails.org/browser/trunk/activesupport/lib/active_support/inflections.rb (MIT license)
//           http://www.fortunecity.com/bally/durrus/153/gramch13.html
//           http://www2.gsu.edu/~wwwesl/egw/crump.htm
//
// Changes (12/17/07)
//   Major changes
//   --
//   Fixed irregular noun algorithm to use regular expressions just like the original Ruby source.
//       (this allows for things like fireman -> firemen
//   Fixed the order of the singular array, which was backwards.
//
//   Minor changes
//   --
//   Removed incorrect pluralization rule for /([^aeiouy]|qu)ies$/ => $1y
//   Expanded on the list of exceptions for *o -> *oes, and removed rule for buffalo -> buffaloes
//   Removed dangerous singularization rule for /([^f])ves$/ => $1fe
//   Added more specific rules for singularizing lives, wives, knives, sheaves, loaves, and leaves and thieves
//   Added exception to /(us)es$/ => $1 rule for houses => house and blouses => blouse
//   Added excpetions for feet, geese and teeth
//   Added rule for deer -> deer

// Changes:
//   Removed rule for virus -> viri
//   Added rule for potato -> potatoes
//   Added rule for *us -> *uses

class Inflect
{
    static $plural = array(
        '/(quiz)$/i'               => "$1zes",
        '/^(ox)$/i'                => "$1en",
        '/([m|l])ouse$/i'          => "$1ice",
        '/(matr|vert|ind)ix|ex$/i' => "$1ices",
        '/(x|ch|ss|sh)$/i'         => "$1es",
        '/([^aeiouy]|qu)y$/i'      => "$1ies",
        '/(hive)$/i'               => "$1s",
        '/(?:([^f])fe|([lr])f)$/i' => "$1$2ves",
        '/(shea|lea|loa|thie)f$/i' => "$1ves",
        '/sis$/i'                  => "ses",
        '/([ti])um$/i'             => "$1a",
        '/(tomat|potat|ech|her|vet)o$/i'=> "$1oes",
        '/(bu)s$/i'                => "$1ses",
        '/(alias)$/i'              => "$1es",
        '/(octop)us$/i'            => "$1i",
        '/(ax|test)is$/i'          => "$1es",
        '/(us)$/i'                 => "$1es",
        '/s$/i'                    => "s",
        '/$/'                      => "s"
    );
    
    static $singular = array(
        '/(quiz)zes$/i'             => "$1",
        '/(matr)ices$/i'            => "$1ix",
        '/(vert|ind)ices$/i'        => "$1ex",
        '/^(ox)en$/i'               => "$1",
        '/(alias)es$/i'             => "$1",
        '/(octop|vir)i$/i'          => "$1us",
        '/(cris|ax|test)es$/i'      => "$1is",
        '/(shoe)s$/i'               => "$1",
        '/(o)es$/i'                 => "$1",
        '/(bus)es$/i'               => "$1",
        '/([m|l])ice$/i'            => "$1ouse",
        '/(x|ch|ss|sh)es$/i'        => "$1",
        '/(m)ovies$/i'              => "$1ovie",
        '/(s)eries$/i'              => "$1eries",
        '/([^aeiouy]|qu)ies$/i'     => "$1y",
        '/([lr])ves$/i'             => "$1f",
        '/(tive)s$/i'               => "$1",
        '/(hive)s$/i'               => "$1",
        '/(li|wi|kni)ves$/i'        => "$1fe",
        '/(shea|loa|lea|thie)ves$/i'=> "$1f",
        '/(^analy)ses$/i'           => "$1sis",
        '/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i'  => "$1$2sis",        
        '/([ti])a$/i'               => "$1um",
        '/(n)ews$/i'                => "$1ews",
        '/(h|bl)ouses$/i'           => "$1ouse",
        '/(corpse)s$/i'             => "$1",
        '/(us)es$/i'                => "$1",
        '/s$/i'                     => ""
    );
    
    static $irregular = array(
        'move'   => 'moves',
        'foot'   => 'feet',
        'goose'  => 'geese',
        'sex'    => 'sexes',
        'child'  => 'children',
        'man'    => 'men',
        'tooth'  => 'teeth',
        'person' => 'people'
    );
    
    static $uncountable = array( 
        'sheep', 
        'fish',
        'deer',
        'series',
        'species',
        'money',
        'rice',
        'information',
        'equipment'
    );
    
    public static function pluralize( $string ) 
    {
        // save some time in the case that singular and plural are the same
        if ( in_array( strtolower( $string ), self::$uncountable ) )
            return $string;
            
    
        // check for irregular singular forms
        foreach ( self::$irregular as $pattern => $result )
        {
            $pattern = '/' . $pattern . '$/i';
            
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string);
        }
        
        // check for matches using regular expressions
        foreach ( self::$plural as $pattern => $result )
        {
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string );
        }
        
        return $string;
    }
    
    public static function singularize( $string )
    {
        // save some time in the case that singular and plural are the same
        if ( in_array( strtolower( $string ), self::$uncountable ) )
            return $string;

        // check for irregular plural forms
        foreach ( self::$irregular as $result => $pattern )
        {
            $pattern = '/' . $pattern . '$/i';
            
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string);
        }
        
        // check for matches using regular expressions
        foreach ( self::$singular as $pattern => $result )
        {
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string );
        }
        
        return $string;
    }
    
    public static function pluralize_if($count, $string)
    {
        if ($count == 1)
            return "1 $string";
        else
            return $count . " " . self::pluralize($string);
    }
}

ActionScript:

package
{
public class Inflect
{
    private static var plural : Array = [
        [/(quiz)$/i,                     "$1zes"],
        [/^(ox)$/i,                      "$1en"],
        [/([m|l])ouse$/i,                "$1ice"],
        [/(matr|vert|ind)ix|ex$/i,       "$1ices"],
        [/(x|ch|ss|sh)$/i,               "$1es"],
        [/([^aeiouy]|qu)y$/i,            "$1ies"],
        [/(hive)$/i,                     "$1s"],
        [/(?:([^f])fe|([lr])f)$/i,       "$1$2ves"],
        [/(shea|lea|loa|thie)f$/i,       "$1ves"],
        [/sis$/i,                        "ses"],
        [/([ti])um$/i,                   "$1a"],
        [/(tomat|potat|ech|her|vet)o$/i, "$1oes"],
        [/(bu)s$/i,                      "$1ses"],
        [/(alias|status)$/i,             "$1es"],
        [/(octop)us$/i,                  "$1i"],
        [/(ax|test)is$/i,                "$1es"],
        [/(us)$/i,                       "$1es"],
        [/s$/i,                          "s"],
        [/$/i,                           "s"]
    ];
    
    private static var singular : Array = [
        [/(quiz)zes$/i,             "$1"],
        [/(matr)ices$/i,            "$1ix"],
        [/(vert|ind)ices$/i,        "$1ex"],
        [/^(ox)en$/i,               "$1"],
        [/(alias|status)es$/i,      "$1"],
        [/(octop|vir)i$/i,          "$1us"],
        [/(cris|ax|test)es$/i,      "$1is"],
        [/(shoe)s$/i,               "$1"],
        [/(o)es$/i,                 "$1"],
        [/(bus)es$/i,               "$1"],
        [/([m|l])ice$/i,            "$1ouse"],
        [/(x|ch|ss|sh)es$/i,        "$1"],
        [/(m)ovies$/i,              "$1ovie"],
        [/(s)eries$/i,              "$1eries"],
        [/([^aeiouy]|qu)ies$/i,     "$1y"],
        [/([lr])ves$/i,             "$1f"],
        [/(tive)s$/i,               "$1"],
        [/(hive)s$/i,               "$1"],
        [/(li|wi|kni)ves$/i,        "$1fe"],
        [/(shea|loa|lea|thie)ves$/i,"$1f"],
        [/(^analy)ses$/i,           "$1sis"],
        [/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i,  "$1$2sis"],        
        [/([ti])a$/i,               "$1um"],
        [/(n)ews$/i,                "$1ews"],
        [/(h|bl)ouses$/i,           "$1ouse"],
        [/(corpse)s$/i,             "$1"],
        [/(us)es$/i,                "$1"],
        [/s$/i,                     ""]
    ];
    
    private static var irregular : Array = [
        ['move'   , 'moves'],
        ['foot'   , 'feet'],
        ['goose'  , 'geese'],
        ['sex'    , 'sexes'],
        ['child'  , 'children'],
        ['man'    , 'men'],
        ['tooth'  , 'teeth'],
        ['person' , 'people']
    ];
    
    private static var uncountable : Array = [
        'sheep', 
        'fish',
        'deer',
        'series',
        'species',
        'money',
        'rice',
        'information',
        'equipment'
    ];
    
    public static function pluralize( string : String ) : String 
    {
        var pattern : RegExp;
        var result : String;
            
        // save some time in the case that singular and plural are the same
        if (uncountable.indexOf(string.toLowerCase()) != -1)
          return string;
          
        // check for irregular singular forms
        var item : Array;
        for each ( item in irregular )
        {
            pattern = new RegExp(item[0] + "$", "i");
            result = item[1];

            if (pattern.test(string))
            {
                return string.replace(pattern, result);
            }
        }
       
        // check for matches using regular expressions
        for each ( item in plural)
        {
            pattern = item[0];
            result = item[1];
           
            if (pattern.test(string))
            {
                return string.replace(pattern, result);
            }
        }
       
        return string;
    }
    
    public static function singularize( string : String ) : String
    {
        var pattern : RegExp;
        var result : String

        // save some time in the case that singular and plural are the same
        if (uncountable.indexOf(string.toLowerCase()) != -1)
            return string;
          
        // check for irregular singular forms
        var item : Array;
        for each ( item in irregular )
        {
            pattern = new RegExp(item[1] + "$", "i");
            result = item[0];

            if (pattern.test(string))
            {
                return string.replace(pattern, result);
            }
       }
       
       // check for matches using regular expressions
       for each ( item in singular)
       {
            pattern = item[0];
            result = item[1];
           
            if (pattern.test(string))
            {
                return string.replace(pattern, result);
            }
       }
       
       return string;

    }
    
    public static function pluralizeIf(count : int, string : String) : String
    {
        if (count == 1)
            return "1 " + string;
        else
            return count.toString() + " " + pluralize(string);
    }
}
}

Ruby on Rails (use this to replace your Inflect.rb):

Inflector.inflections do |inflect|
    inflect.plural(/$/, 's')
    inflect.plural(/s$/i, 's')
    inflect.plural(/(us)$/i, '\\1es')
    inflect.plural(/(ax|test)is$/i, '\\1es')
    inflect.plural(/(octop)us$/i, '\\1i')
    inflect.plural(/(alias)$/i, '\\1es')
    inflect.plural(/(bu)s$/i, '\\1ses')
    inflect.plural(/(tomat|potat|ech|her|vet)o$/i, '\\1oes')
    inflect.plural(/([ti])um$/i, '\\1a')
    inflect.plural(/sis$/i, 'ses')
    inflect.plural(/(shea|lea|loa|thie)f$/i, '\\1ves')
    inflect.plural(/(?:([^f])fe|([lr])f)$/i, '\\1\\2ves')
    inflect.plural(/(hive)$/i, '\\1s')
    inflect.plural(/([^aeiouy]|qu)y$/i, '\\1ies')
    inflect.plural(/(x|ch|ss|sh)$/i, '\\1es')
    inflect.plural(/(matr|vert|ind)(?:ix|ex)$/i, '\\1ices')
    inflect.plural(/([m|l])ouse$/i, '\\1ice')
    inflect.plural(/^(ox)$/i, '\\1en')
    inflect.plural(/(quiz)$/i, '\\1zes')
 	
    inflect.singular(/s$/i, '')
    inflect.singular(/(us)es$/i, '\\1')
    inflect.singular(/(corpse)s$/i, '\\1')
    inflect.singular(/(h|bl)ouses$/i, '\\1ouse')
    inflect.singular(/(n)ews$/i, '\\1ews')
    inflect.singular(/([ti])a$/i, '\\1um')
    inflect.singular(/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i, '\\1\\2sis')
    inflect.singular(/(^analy)ses$/i, '\\1sis')
    inflect.singular(/(shea|loa|lea|thie)ves$/i, '\\1f')
    inflect.singular(/(li|wi|kni)ves$/i, '\\1fe')
    inflect.singular(/(hive)s$/i, '\\1')
    inflect.singular(/(tive)s$/i, '\\1')
    inflect.singular(/([lr])ves$/i, '\\1f')
    inflect.singular(/([^aeiouy]|qu)ies$/i, '\\1y')
    inflect.singular(/(s)eries$/i, '\\1eries')
    inflect.singular(/(m)ovies$/i, '\\1ovie')
    inflect.singular(/(x|ch|ss|sh)es$/i, '\\1')
    inflect.singular(/([m|l])ice$/i, '\\1ouse')
    inflect.singular(/(bus)es$/i, '\\1')
    inflect.singular(/(o)es$/i, '\\1')
    inflect.singular(/(shoe)s$/i, '\\1')
    inflect.singular(/(cris|ax|test)es$/i, '\\1is')
    inflect.singular(/(octop|vir)i$/i, '\\1us')
    inflect.singular(/(alias)es$/i, '\\1')
    inflect.singular(/^(ox)en/i, '\\1')
    inflect.singular(/(vert|ind)ices$/i, '\\1ex')
    inflect.singular(/(matr)ices$/i, '\\1ix')
    inflect.singular(/(quiz)zes$/i, '\\1')
 	
    inflect.irregular('person', 'people')
    inflect.irregular('tooth', 'teeth')
    inflect.irregular('man', 'men')
    inflect.irregular('child', 'children')
    inflect.irregular('sex', 'sexes')
    inflect.irregular('goose', 'geese')
    inflect.irregular('foot', 'feet')
    inflect.irregular('move', 'moves')
 	
    inflect.uncountable(%w(equipment information rice money species series deer fish sheep))
end

As I was talking about using objects as enums, someone made a comment about the lack of private and protected constructors. I know that the this is a sore spot, so I thought I’d explain my view of how we got here, and give my two cents.

The problem is that unlike what we did with ActionScript 2, we are working tightly with people from Mozilla and others to standardize on ECMAScript edition 4. The ECMAScript standard is not final, but we are adhering as closely as we can to the spec as it develops.
More »

FAB – Flex/AJAX Bridge – is a library created by Ely Greenfield, who is a good friend and Flex Architect.

FAB lets you control Flex applications using JavaScript. Method calls just work, and getters and setters are converted to method calls (because browsers don’t support getters and setters yet).

You can even attach event listeners from JavaScript and pass function objects back and forth. For example, you can create an MXML file with a button in it and drive all of the logic from within your HTML/JavaScript.

MXML:
—
<mx:Application xmlns:mx=”http://www.macromedia.com/2005/mxml”>
    <fab:FABridge xmlns:fab=”bridge.*” />
    <mx:Button id=”okButton” label=”OK” />
</mx:Application>

JavaScript:
—
function init()
{
    var flexApp = FABridge.flash.root();
    flexApp.okButton().addEventListener(“click”, handleClick);
}

function handleClick(event)
{
    // handle the click event here.
}

You can read more about it on Ely’s blog, which I predict will be worth reading.

http://www.quietlyscheming.com/blog/2006/03/06/flex-and-ajax/

As promised, here are my slides and notes from Flashforward. Some things you will need to know:

1. The layout syntax uses the new beta 2 syntax, which is not out yet.
2. The notes cover a bit less material than the slides. That’s because the notes were finalized before the slides were, in order to get them printed on paper for conference attendees. If I have time, I may extend the notes but with so much going on, I am not sure I will have time to do this.

[Slides – ppt] [Slides – pdf]
[Speaker notes – doc] [Speaker notes – pdf]