Dakin Design

JavaScript switch statement uses type checking

admin — Mon, 02 Aug 2010 05:38:43 +0000

I was just bitten by this:

    var foo = "2";
    var bar = 2;

    switch (parseInt(foo)) {
        case bar:
            alert("match");
            break;
        default:
            alert("no match");
    }

That code should alert “match” – but take out the parseInt, and you get “no match.”

It looks like the switch statement uses type checking (i.e. ===, not ==) in FireFox 3.6.8 for Mac (haven’t tried other browsers).

Fun with Google Voice

admin — Thu, 22 Apr 2010 01:54:22 +0000

Love it.

Best Homepage of the Day

admin — Tue, 20 Apr 2010 06:52:25 +0000

http://miketaylr.com

jQuery Event Delegation and Nested Tables

admin — Sat, 06 Feb 2010 23:31:56 +0000

I was reading a blog post about jQuery event delegation by Karl Swedberg yesterday. One corner case I found in his examples is dealing with nested DOM elements of the same type (e.g. divs within divs, or in the following example tables within tables).

Here’s a solution (albeit possibly not the best) that makes use of jQuery’s parentsUntil() method, added in version 1.4:

          ”http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>
      xmlns:v=”urn:schemas-microsoft-com:vml”>

[Nothing clicked]

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Deleting Multiple Items from a JavaScript Array

admin — Wed, 18 Nov 2009 20:02:13 +0000

Here’s a handy way to delete multiple items (that may not be contiguous) from a JavaScript array.

This hinges around using splice() in a for() loop. The trouble is that every time you slice, the index of each of the following items in the array gets decremented but you’re still increasing your index variable with each iteration.

For example:

var arr = [ { name: 'a', active: true }, { name: 'b', active: false }, { name: 'c', active: true }, { name: 'd', active: false }, { name: 'e', active: true } ];


// let's kill the inactive objects

var kill = [];

for (var i = 0; i < arr.length; i++) {

    if (!arr[i].active)

        kill.push(i);

}

// now 'kill' contains [1, 3]

We're fine so far: now we have the indexes that we want to remove. Here's where the trouble starts:

// remove inactive elements from array - BAD for (var i = 0; i < kill.length; i++) arr.splice(kill[i], 1);

As mentioned above, this is bad because each time you remove an element from the array, the following elements will all have their indexes decremented. That means that the next "kill" index you come across will reference the wrong element!

Here's a simple way to mitigate:

// remove inactive elements from array - GOOD for (var i = 0; i < kill.length; i++) arr.splice(kill[i] - i, 1);

Note the change in the splice index from "kill[i]" to "kill[i] - i", which accounts for the decremented array indexes.

By the way, you may be asking, "Why not use 'delete'?" Well, delete leaves holes in your array, which we don't want.

You may also be asking, "Why not use foreach() instead of for(), thereby, bypassing the need for an index variable?" Well, it's unsafe to use foreach() on an array. You should only ever use foreach() on an object, for reasons that I won't get into here.

Hope this helps someone.

admin — Fri, 14 Aug 2009 19:46:59 +0000

Question:

Who can get Eric Clapton to join him for a sold-out modern day blues show at the prestigious Royal Albert Hall in London?

Answer:

How To Project On 3D Geometry

admin — Mon, 08 Jun 2009 16:40:28 +0000

Awesome: http://vvvv.org/tiki-index.php?page=How+To+Project+On+3D+Geometry

Obama at ASU

admin — Sun, 24 May 2009 06:56:11 +0000

President Obama gave the 2009 commencement speech at the Arizona State University. Here’s an excerpt that I highly agree with:

“We’ve become accustomed to our economic dominance in the world, forgetting that it wasn’t reckless deals and get-rich-quick schemes that got us where we are, but hard work and smart ideas, quality products, and wise investments.

“We started taking shortcuts. We started living on credit instead of building up savings. We saw businesses focus more on rebranding and repackaging than innovating and developing new ideas that improve our lives.”

It’s no surprise that the tech world is getting hit so hard by this recession. Instead of developing quality products and innovating on new ideas, so many companies have been lusting after the quick venture: a slightly different way of targeted advertising, a flailing landrush for Facebook integration, and more useless iPhone applications.

As Tim O’Reilly says: work on stuff that matters. Keep an eye on the companies that survive this recession; they’re likely to come out of it with guns blazing.

Toward the end of his speech, President Obama commented on giving back:

“One student said it best when she spoke about her senior engineering project building medical devices for people with disabilities in a village in Africa. Her professor showed a video of the folks they had been helping, and she said, ‘When we saw the people on the videos, we began to feel a connection to them. It made us want to be successful for them.’

“Think about that. It made us want to be successful for them. That’s a great motto for all of us. Find somebody to be successful for. Raise their hopes. Rise to their needs.”

SCU kids: sound familiar? Those comments summarize the foundation of Jesuit education: do well to do good.

Obama’s full speech, with introduction by the president of ASU: http://www.youtube.com/v/Qbel5MhtDq4

Robert Plant totally looks like King Theoden

admin — Fri, 24 Apr 2009 06:51:26 +0000

Doesn't he?

Rembering Shane

admin — Fri, 03 Apr 2009 01:01:55 +0000

Tribute to Shane McConkey