JS in a href.......

allworknoplay · 04-21-2009, 10:04 PM

can someone explain to me fundamentally what this does?

<a href="javascript:myFunction();">

I assume that the first part "javascript" is calling
my javascript up in the header?

<script type="text/javascript"></script>

And myFunction is calling a function that is within that script?

So hypothetically, if I did this, then it's the same philosophy?

<script type="text/whatever"></script>

<a href="whatever:myFunction();">

Also, why is it that when calling a function outside of the
javascript tags, you use the parenthesis "()"..

But within it, you don't? Like this...

Code:

<script type="text/javascript">

var clickCount = 0;
function documentClick(){
    document.getElementById('clicked').value = ++clickCount;
}
document.onclick = documentClick;

</script>

How come:

document.onclick = documentClick;

Doesn't use parenthesis? Shouldn't it be?

document.onclick = documentClick();

Kalle · 04-21-2009, 10:47 PM

Quote:

Originally Posted by allworknoplay

can someone explain to me fundamentally what this does?

<a href="javascript:myFunction();">

I assume that the first part "javascript" is calling
my javascript up in the header?

This executes a javascript event when the link is clicked on

Quote:

Originally Posted by allworknoplay

Yes

Quote:

Originally Posted by allworknoplay

So hypothetically, if I did this, then it's the same philosophy?

<script type="text/whatever"></script>

<a href="whatever:myFunction();">

No because the "javascript" protocol (which isn't actually a protocol) has a special meaning to the browsers.

Quote:

Originally Posted by allworknoplay

Also, why is it that when calling a function outside of the
javascript tags, you use the parenthesis "()"..

But within it, you don't? Like this...

Code:

<script type="text/javascript">

var clickCount = 0;
function documentClick(){
    document.getElementById('clicked').value = ++clickCount;
}
document.onclick = documentClick;

</script>

How come:

document.onclick = documentClick;

Doesn't use parenthesis? Shouldn't it be?

document.onclick = documentClick();

Thats because you assign a callback to the event, if you call it directly it will be the result of the "documentClick()" function, which returns null (void).

allworknoplay · 04-21-2009, 11:04 PM

Quote:

Originally Posted by Kalle

This executes a javascript event when the link
No because the "javascript" protocol (which isn't actually a protocol) has a special meaning to the browsers.

Thats because you assign a callback to the event, if you call it directly it will be the result of the "documentClick()" function, which returns null (void).

Great thanks, that clears it up.

So the browsers just "naturally" understand what to do when you have "a href=javascript:whatever()".....

I hope DOM isn't that hard, I'll be jumping on that this weekend....

Kalle · 04-22-2009, 03:44 PM

DOM is pretty straigth forward once you gasped the basic of it, you will find the MSDN Library more than excellent for DOM references:
http://msdn.microsoft.com/en-us/library/aa155133.aspx

-> HTML & DHTML (Dynamic HTML)

When you view the CSS reference on MSDN you will also be able to see the scripting names for that style like:

HTML Code:

<input type="button" onclick="this.backgroundColor = '#000000';" value=" Click me " />

same goes for the HTML reference, you will see which events and actions that apply to each tag.

allworknoplay · 04-22-2009, 03:46 PM

Quote:

Originally Posted by Kalle

DOM is pretty straigth forward once you gasped the basic of it, you will find the MSDN Library more than excellent for DOM references:
http://msdn.microsoft.com/en-us/library/aa155133.aspx

-> HTML & DHTML (Dynamic HTML)

When you view the CSS reference on MSDN you will also be able to see the scripting names for that style like:

HTML Code:

<input type="button" onclick="this.backgroundColor = '#000000';" value=" Click me " />

same goes for the HTML reference, you will see which events and actions that apply to each tag.

What is the difference between DHTML and Ajax?

Kalle · 04-22-2009, 06:10 PM

Quote:

Originally Posted by allworknoplay

What is the difference between DHTML and Ajax?

DHTML is an rather old term for HTML that may change during browsing, for example an event that occurs when you click a button which may spawn something. But in theory yes then AJAX can be classified as DHTML.