Modifying a JavaScript Function

[TWTCommish]

Hi,

I'm using some code to generate a pop-up upon the clicking of a link. Here's the code I have in my HEAD tags:

<script language="JavaScript">
<!--
function PopWindow()
{ 
window.open('page.html','popup','width=550,height=400,menubar=no,scrollbars=yes,toolbar=no,
location=no,directories=no,resizable=yes,top=50,left=50'); 
}
//-->
</script>

Here's what I use to invoke an instace of that function:


<a href="JavaScript:PopWindow()">Open Window</a>


I'd like to, if possible, switch things around a bit so the page is not specified in the function, but so I can specify it each time I call the function, something like this:


<a href="JavaScript:PopWindow(page.html)">Open Window</a>


I've tried modifying the code in several different ways, but an error always follows. Any help would be greatly appreciated.

[Hierophant]

<script language="JavaScript">
<!--
function PopWindow(pagename)
{ 
window.open(pagename,'popup','width=550,height=400,menubar=no,scrollbars=yes,toolbar=no,
location=no,directories=no,resizable=yes,top=50,left=50'); 
}
//-->
</script>

[reachmk]

Make sure the window.open line is in a single line and not breaks up in 2 lines in your script.

<script language="JavaScript">
<!--
function PopWindow(page)
{ 
window.open(page,'popup','width=550,height=400,menubar=no,scrollbars=yes,toolbar=no,location=no,directories=no,resizable=yes,top=50,left=50'); 
}
//-->
</script>

And call like this:

<a href="JavaScript:PopWindow('page.htm')">Open Window</a>

Dont forget the Single Quotes in the above code. 'page.htm'

Hope it helps.

[Edit Note] i took much time in replying, it seems. Wayne has already answered.

[Edited by reachmk on 11-15-2000 at 10:05 AM]

[TWTCommish]

Thanks guys - surprisingly I came very close to that in my attempt at modification, but I think I had single quotes where I shouldn't have, and lacked them in other places.

Thanks to both!

[Vincent Puglia]

Hi Chris,

I thought I'd expand on what Wayne and reachmk posted; hope you don't mind.

The passing of arguments (in this case 'page.html') to a function is the better programming design for the following two (at the minimum) reasons:

1) It takes one step away from hard-coding and one step towards OOP (object oriented programming).
2) It enables you to use the same function for any number of applications

If you have a number of pages you need to open with various links, you can put your sources in an array and then access them that way. For example:

var myLinks = new Array();
myLinks[0] = 'page1.html';
myLinks[1] = 'page2.html';


window.open(myLinks[0],'popup',.......blahblah....

You can then put the array in a js file, include the file in all necessary documents, and access the array from there. This will provide you with a one-page source for editing purposes.

Vinny

[Hierophant]

Thanks for a good quick beginning tutorial on parameters and creating re-usable code. You covered the basics of both in a few short sentences.

What he didn't mention is you can use the same techniques mentioned above in any programming language available today. This will prevent a lot of wheel re-inventing

[TWTCommish]

Absolutely. I'm trying to included common files and things like that whenever possible - still having a *VERY* hard time grasping OOP though - I'm searching for decent tutorials on the subject.

Hopefully, when OOP "clicks" for me, I'll be able to take a major leap forward and get into some more advanced programming. Sure is tough, though! It's annoying to know the basics of several languages - just enough to write some fairly useful things, but not enough to say I really "know" the language.

[creole]

AMEN Chris...well said. I struggle with that too as I "know" Javascript and am learning PHP. It's hard to get past the basic level.

[etLux]

Just hang in there -- the OOP will come... Spend some time being certain to understand the key concepts -- objects, properties, methods -- and what *exactly* they are.

This crucial step is where many get bogged down, especially those used to older languages that are completely sequential.

[Vincent Puglia]

Hi,

OOPs, or what I don't know, helps

If you want to start learning OOP, take all of your functions/scripts and start generalizing/un-hardcoding them. That is, find a function and remove any direct mention of a value, object name, etc. If possible, functions should be as totally ignorant of what is being passed to them as possible.

For example, most people would calculate a geometric shape's area by creating a function for each shape (calcCircle, calcRectangle, etc). To paraphrase Shakespeare, though, an area under any shape is still an area. Now there are many ways to do this, but the following in one (another if I remember right is at my site in the "Arguments Property" tutorial.)


function calcArea()
{
var area = 0;
switch (arguments.length)
{
case 2:
if (arguments[0] == 'c') // it's a circle
area = arguments[1] * 3.14;
else // it's a square
area = arguments[1] * arguments[1];
break;
case 3:
area = arguments[1] * arguments[2];
break;
default:
area = ....errorCode goes here...
}
return (area);
}

Vinny