Disqus - Latest Comments for jimbojw

Re: Thing that makes life just grand of the day: seven databases in song

jimbojw — Fri, 22 Jun 2012 14:34:01 -0000

Actually, I'm about as far away as possible and still be in the continental US. I'm based out of Boston :)

Re: http://sevenweeks.org/post/24891440010

jimbojw — Wed, 13 Jun 2012 22:42:36 -0000

Hi Mike,

We included the same Seven Databases that we wrote about in our book:

The really short story is that Cassandra draws inspiration from both columnar design and Dynamo-esque sharding. We felt Hbase and Riak we're better representatives of BigTable and Dynamo respectively.

Re: Thing that makes life just grand of the day: seven databases in song

jimbojw — Wed, 13 Jun 2012 19:41:21 -0000

Thanks for the write-up! Glad you liked it :)

Re: Romney Wins New Hampshire Republican Primary, AP Projects - Businessweek

jimbojw — Tue, 10 Jan 2012 21:26:00 -0000

Who came in second?

Re: A closer look at super-references in JavaScript and ECMAScript.next

jimbojw — Wed, 30 Nov 2011 10:17:25 -0000

I haven't been following ES past 5, and even that I'm not really up to speed on. So I'll have to claim ignorance about future features. If it's true that static is coming to ES6, I don't see how this differs from the failure that was ES4 (which I, for one, was happy to see die off).

Also, thanks much for your code example. It seems to confirm my suspicion that the concept of "super" is a convienence variable for accessing the prototypal grandparent of "this". I didn't know about getPrototypeOf, but I'm glad to see that the language is getting it---this was sorely needed.

Re: A closer look at super-references in JavaScript and ECMAScript.next

jimbojw — Wed, 30 Nov 2011 10:10:55 -0000

Thanks for taking the time to respond. I'll try to clarify my confusion.

> " A method is currently executed. It is stored in an object. The search for a super-property starts in the prototype of that object."
I have a pretty good mental model of how "this" works in JS. When you call a function using the method invocation syntax (ex: foo.bar()), then "this" inside the function points to whatever was on the left-hand side of the period prior to the invocation (ex: foo).

Now consider super. When you call a function using method invocation syntax (ex: foo.bar()), then "super" inside the function points to ... "this"'s prototypal parent? "this"'s prototypal parent's prototypal parent?

I believe it's the latter. So if June was made from new Employee() (meaning Employee.prototype is June's prototypal parent), then we expect June.describe() to assign "super" to Person, right? That would be June's prototypal grandparent.

What happens when you call a function directly via call() or apply()? (ex: foo.bar.call(null))? In that case, "this" is whatever is passed in explicitly, or the global object (window). What would "super" be?

Under the "this's prototypal grandparent" line of reasoning, if "this" ends up being, say, the global window object, then "super" would be window's prototypal grandparent, which would be Object (maybe)?

> "A property whose value is a function is called a method in JavaScript. Can you elaborate on what you mean by “hence the confusion many developers have around ‘this’”? "

According to Wikipedia[1]:

"The association between class and method is called binding. A method associated with a class is said to be bound to the class. Methods can be bound to a class at compile time (static binding) or to an object at runtime (dynamic binding)."

This causes two problems in JavaScript: first, there are no classes, only prototypal inheritance, so the terminology gets confusing. Second, JavaScript has no "compile time," there is only runtime. Developers are routinely tripped up by "this" because they want to do the following:

someDomElement.onsomething = myObject.someMethod;

The reality is that when the JS engine executes someMethod, it does so outside the context of myObject, so "this" is not what the developer expected when they originally wrote the function or assigned it to a handler.

The quality of being a "method" in the OO sense is more than just being a property of an object which happens to be a function. Being a method requires a binding to a class. This binding doesn't exist until the function is executed, at which point the JavaScript engine decides what "this" ought to be.

My problem with "super" is that it's a concept steeped in the classical inheritance mindset and depends on ideas like classes, instances and methods---all of which are absent in varying degrees JavaScript.

[1] http://en.wikipedia.org/wik...

Re: A closer look at super-references in JavaScript and ECMAScript.next

jimbojw — Tue, 29 Nov 2011 09:42:30 -0000

I don't understand how super can even be determined. The statement "the prototype of the object in which the current method is located" doesn't make sense to me.

JavaScript doesn't have "methods" per se. The term method implies a binding, and in JavaScript, there is none until when the function is executed, hence the confusion many developers have around "this".

So the idea of looking up the meaning of super becomes problematic. What if I do something like var foo = Employee.prototype.describe; foo(). What should super be? Should the JS engine know that foo's target (a function named 'me') happened to have been assigned at one time to a member named describe on an object called Employee.prototype?

Re: Understanding the JavaScript new keyword

jimbojw — Tue, 09 Aug 2011 15:28:24 -0000

Hi Jon,

The short answer is, well, because that's not the way the language works :)

You are correct that a function in JS is indeed an object, and so you could set the prototype to point to a function, but I wouldn't recommend it. I tried some experiments, and the results are pretty weird to me.

Probably better to use Object.create() to set up prototypal inheritance anyway, that way it's obvious how things relate to each other.

Re: BlackBerry PlayBook Developer Promotion Information

jimbojw — Thu, 09 Dec 2010 16:32:28 -0000

Is there a final submission deadline? If so, when is it?

Re: To VC or Not to VC

jimbojw — Tue, 26 Oct 2010 12:44:11 -0000

I think this is a fantastic question. The money part of the equasion used to be necessary, but increasingly it's irrelevant. With the pervasiveness of cheap web services (hosting, CDN, etc), buying hardware isn't generally a barrier.

For me, it's about time. Capital affords hiring bright people to help execute on the vision. Without that, you're on your own, grinding it out in the off hours after your regular job.

I believe in the ideal of doing it without capital, but the reality is that it severely limits the scope of projects you might otherwise be able to tackle (due to lack of time, and no help).

Re: An Accessible Way To Stop Your Content From Flashing (FOUC) - Alex Sexton

jimbojw — Tue, 28 Sep 2010 11:13:02 -0000

Ugh, garbled my code. Another attempt:

Idea: <body class="noscript"><script>document.body.className="";</script> <style>.noscript .stuffIDontWantToFlash { display: inherit; }</style>

Re: An Accessible Way To Stop Your Content From Flashing (FOUC) - Alex Sexton

jimbojw — Tue, 28 Sep 2010 11:11:16 -0000

Idea: document.body.className='';... then, .noscript .stuffIDontWantToFlash { display: inherit; }

Re: Socializing Error Message Pages

jimbojw — Mon, 27 Sep 2010 17:59:42 -0000

If your users are kind-hearted, forgiving souls who genuinely want the experience of others to improve as a result of their experience, yes, this will work well. Some people are that way.

On the other hand, if your users are, perhaps, less than happy with your company or service, they may have less than honorable things to write on said error page wiki. Just sayin.

Re: Find the closest Power of 2 with JavaScript - Bocoup

jimbojw — Fri, 18 Jun 2010 23:07:27 -0000

I haven't checked Mathieu's solution, but I agree that a bitwise calculation is better than calling through to Math functions.

And even if you choose to go the Math route, I'd recommend making local references to reduce scope and object lookups, and bitshift 0 instead of round.

Ex:

var nearestPow2 = (function(Math){
var
pow = Math.pow,
log = Math.log;
return function nearestPow2( aSize ){
return pow( 2, ( log( aSize ) / log( 2 ) ) << 0 );
};
})(Math);

Re: DailyJS: Romano, Hexlib, Namespace

jimbojw — Fri, 28 May 2010 15:13:35 -0000

Thanks for the shout-out about hexlib! If you find any bugs/quirks, please let me know.

Re: JavaScript call and apply

jimbojw — Mon, 26 Apr 2010 12:32:39 -0000

Thanks paulur!

Re: Simple prototypal inheritance

jimbojw — Tue, 06 Oct 2009 09:43:35 -0000

Hi Mark,

Thanks for the tip! To be honest, I've paid no attention at all to EcmaScript 5 - I wasn't even aware that it introduced an Object.create function.

Of course, you're right about keeping new functions out of Object. I'm of the mindset that JavaScript libraries should seek to isolate changes from core language features. Crockford's decision to introduce create as a property of Object seemed odd to me when I read it - the fewer globals and modifications to existing objects the better.

Thanks again!

Re: Simple prototypal inheritance

jimbojw — Mon, 05 Oct 2009 13:34:55 -0000

Hi Skozlov,

Thanks for taking the time to read my article! That's a great question. Here's a simple example of the Employee prototype, rewritten to override the greet method:

var Employee = Object.create(Person, { greet: function(person) { if (person) alert("Hello " + person + ", I'm " + this.name); else Person.greet.call(this); }, status: function() { alert("I'm " + this.name + ", the " + this.title); } });

In the above case, we want to alert a special message if a parameter "person" has been passed into greet(), but fall back to Person.greet() if one hasn't.

For more info on call(), check out my previous article: JavaScript call and apply

Hope this helps!

Re: Persistent_client_side_database

jimbojw — Mon, 28 Sep 2009 10:14:48 -0000

Hi reycat67,

Thanks for taking the time to comment! Trephine is the bridge that allows coding Java through JavaScript. This demo shows how trephine can load and use a remote Java library called HSQLDB.

It's possible that HSQLDB supports federation and/or synchronization of some kind - I'm not sure. In any case, that would be up to the application or library, not trephine.

I'm sure there are Java libraries for remote database synchronization. I haven't studied the topic, so I can't recommend anything off-hand, but a little research ought to turn something up.

Thanks again, and I hope this helps,

-- Jim

Re: Adventures in Rhino - setters and getters

jimbojw — Thu, 27 Aug 2009 16:01:24 -0000

Hi Michael,

Thanks for checking in! I did start the project, but then got away from it again.

I ended up creating a clone of PHP's file_get_contents() function since that was basically all I needed.

I'm still planning to get back to it, as well as writing more articles. Just had some other responsibilities to take care of lately.

Thanks again!

Re: Detecting JavaScript function tampering - part 3

jimbojw — Fri, 10 Jul 2009 10:01:48 -0000

Hi Ivo,

That's an excellent point! I hadn't considered that.

The next level deeper would be to use Function.prototype.toString.call(methodName) instead of simple concatenation. Of course, then someone could override Function.prototype.toString to return a different value for certain functions.

I'm nearly certain that there's no way to be completely sure that a given function hasn't been modified. That is, the concept of detecting JavaScript function tampering may be an unsolvable problem.

Thanks again for reading and pointing out that loophole!

Re: Site improvements - fighting with Disqus

jimbojw — Wed, 01 Jul 2009 09:09:05 -0000

That's a good point, Darek. I guess it depends on how highly you value the comment content of the pages.

If you have a site where you absolutely depend on the comments in order to create value, then I can see the argument that keeping the comments "in house" is a necessity. On the other hand, if the comments are a secondary feature intended solely to engage the audience and elicit feedback, then it may be less crucial if, say, disqus were to cease providing its services.

Certainly worth thinking about some more, especially in the wake of that Google outtage from a few weeks ago. That made innumerable sites non-functioning simply because browsers couldn't initialize the analytics code.

Re: JavaScript call and apply

jimbojw — Mon, 29 Jun 2009 16:41:43 -0000

Glad to help! Thanks for reading.

Re: JavaScript string building benchmarks

jimbojw — Sat, 16 May 2009 00:15:00 -0000

Hi Phillip,

That's a good idea. Actually, the best thing to do would be to run all the tests on a Windows box so that I can test Firefox 2 and 3, IE 6, 7 and 8, Safari 3 and 4, Chrome and Opera 9 and 10. It would also probably be worth while running all applicable tests on Mac as well (FF, Safari and Opera).

Thanks for running the Safari test - it's good to see that the algorithms behave relative to each other in that browser. Much appreciated!

Re: Major Latency With Google Web Search Gmail

jimbojw — Thu, 14 May 2009 12:10:05 -0000

All google services are effectively dead to me right now (unpingable, slow or no HTTP response).

I never thought I'd have to rethink how I search for information, but today I am. I realized that I have no backup plan, and now I'm learning how to do searches with other engines.

I'm also coming to the conclusion that I need to have a replicated email address with another provider (all emails to either service synced between).

In one sense though, I'm glad this happened, it's retraining me to value the importance of redundancy. Shame on me for not thinking of it sooner.