Let’s use a real example to demostrate what to do: A web page of
biography for a website uses a side menu to select one of several bios
to display in the main area. Doing this in JQuery means that we want
to hook a handler to the click events of each of the <A> element
in the menu. When a menu item is clicked, we will display the
corresponding biography enclosed in a <DIV>

HTML

Here’s the HTML for the menu area and the biography area.
I am using ID’s to distinguish each biography.

Line 1 gives the menu a class of MENU so that we can
easily find it in JQuery.
Line 2 to 4 provide three menu items for the user. Notice
that at line 3 and 4, there are extra styling for the menu text.

Line 7 and on are three DIV’s with ID corresponding to each
of the menu items. Each DIV has a class of BIO, again for
easy selection by JQuery.

<ul> class="menu">
<li><a href="#" id="1">1. Click me to show first bio.</a></li>
<li><a href="#" id="2">2. Click <em>me</em> to show <em>second</em> bio.</a></li>
<li><a href="#" id="3">3. Click <strong>me to show third</strong> bio.</a></li>
</ul>

<div class="bio" id="1">
Biography for person number one.
</div>
<div class="bio" id="2">
Biography for person number two.
</div>
<div class="bio" id="3">
Biography for person number three.
</div>

JQuery: Initialization

The following initialization code first hides all biography divs on load,
and then show just the first one by default. Notice how we use the
:first selector to make selecting the first matching
DIV easy.

Line 9 attach our function click_me to the menu.

$(function(){

    /* Hide all bio divs, then show the very first one. */
    $(".bio").hide();
    $(".bio:first").show();

    /* Hook the onClick function, any A inside an object with
       class menu (UL in this case) */
    $(".menu A").click(click_me);

});

JQuery Handler Function

Here is the handler function that we hooked to the anchors in
the menu. Can you guess what’s the console log output would be?

function click_me(event){

    console.log('clicked');
    /* "this" is DOM element attached by the function */
    console.log('this=' + this);

    /* "event.target" is DOM element receiving the event, can be a child */
    console.log('event.target=' + event.target);

    /* Show the bio selected */
    var s = ".bio[id=" + this.id + "]";
    $(".bio").hide();
    $(s).show();

    /* Silly effect to show the use of $(this). */
    $(this).fadeOut();
    $(this).fadeIn();

};

Here is the explanation:
1. this inside a JQuery event handler is the
DOM element that has the handler attached. This (sic) this is
not necessarily the A link itself. If we have attached the
handler to something else, like the containing DIV, we will
get the DIV DOM element doesn’t matter which inside elements
of the DIV we clicked. In this case we have attached the click_me
function to the anchors (A) themselves, so we are safe
to know that this.id will give us the ID specified
within our A tags.

2. The standard argument passed to the function, event
is the eventObject;
It is a JQuery structure the contains many useful attribute regarding
the (click) event. Specifically event.target is the DOM element received the click event.
Note that it will be “the DOM element that issued the event. This can be the element that registered for the event or a child of it”.

For example, in menu item two, if you clicked on the word “me”, it will
be the span element, not the A element.

3. Finally, when you turn this into $(this),
you are creating a JQuery object out of, well, this.
Turning a DOM element (the A in this case) into a JQuery object
allows you to use all the JQuery functions on it. We do not really
need to do that here, but just as a demonstration, we use $(this)
to fade the menu item out and in. We need to turn the A into a
JQuery object so that we can call the JQuery fadeOut
and fadeIn functions.

You can see a working version of this example here.

How watch out for some useful code samples in future postings.

# first set the buffer tab width to 4 (or whatever you like)

M-x set-variable <return> tab-width < return> 4

# then mark the entire file
C-x h

# do untabify to convert:

M-x untabify <return>

# That’s it!

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Technorati Tags: django

If you were a parent, and your teenager grows up and behave with such manners, professionalism, and people skills, wouldn’t you be proud?

Disclaimer — I have been to other suburb Apple store within a mall and the staff there are definitely not as good. Perhaps it’s a urban twenty-something thing here at the flagship store. So at least make those the role models.

Technorati Tags: apple, children, parenting

Client: Our customers expect us to meet them in San Francisco to run a in person workshop with all of us in a week.

Me: Great. I looked and found a great cheap flight for all of us. Let’s work on what gear to bring and get there one day before to setup.

Their Developer: Wait, I have never been on an airplane.

Me: Really? It will be fun to fly for the first time. I can pick you up at your house and show you around the airport.

Developer: No. I do not want to fly.

Me: Ok. I’ll rent a big SUV and let’s do a road trip. We can work on the presentation on the way.

Developer: No. I am riding my bicycle.

Me: Bicycling from Boston to San Francisco in one week? I don’t think we are that fit.

Developer: I haven’t ridden a bike since I was a kid. But I see people riding bicycles all the time to work.

Me: Yes. Commuting to work is great, exercise and good for the environment.

Developer: See? Let’s go buy some bikes.

Me: Do you really want to tell your customers that you will be there in one week by
riding your bike from Boston to San Francisco?

Developer: …silience…

Me: Ok. I’ll rent a SUV. I’ll make sure it as a GPS. Let’s pack up and leave first thing tomorrow.

Developer: No. We need to buy maps.

Me: GPS is easier.

Developer: I have never seen a GPS. Can you explain how they work?

Me: Sure. There are satellites in the sky, and the GPS receiver takes multiple signals…. Wait. We
don’t have time for this. You can google it and read about it on the way.

Developer: I don’t trust GPS if I don’t know how it works.

Me: GPS has been around for a long time. I’ll let you play with it once we get started.

Developer: I want to get a GPS for my bicycle first to try. Maybe we can just mail them a picture
of us on our bicycles instead?

Journalist should do some research before writing an article just because it is a hot topic.

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iRex 1000

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1. Select any file with the extension you want to change.
2. Click Get Info
3. Down near the bottom, change “open with” to whatever app you want, and
4. also click “change all”

Technorati Tags: apple, Leopard, Mac