Working with Multiple Style Sheets - Swapping alternate style sheets
(Page 4 of 4 )
In order to demonstrate how the previous two JavaScript functions can be used to swap between different alternate style sheets, I'm going to define these sheets, so you can see how they can be activated/deactivated via client-side scripting.
Now, suppose that the respective definitions for these alternate style sheets look like this:
(definition for "red.css" file)
div{
background:#f00;
}
(definition for "green.css" file)
div{
background:#0f0;
}
(definition for "blue.css" file)
div{
background:#00f;
}
(definition for "fonta.css" file)
p{
font: normal 14pt Arial, Helvetica, sans-serif;
}
(definition for "fontb.css" file)
p{
font: normal 18pt Arial, Helvetica, sans-serif;
}
(definition for "fontc.css" file)
p{
font: normal 24pt Arial, Helvetica, sans-serif;
}
As you can see, above I created six alternate style sheets for changing the background color of some DIVs, along with the size of the pertinent paragraphs. Quite understandable, right?
Now, having defined the alternate style sheets, here's the complete signature of the sample (X)HTML file that swaps them via JavaScript:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Strict//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=iso-
8859-1" />
<title>Swapping Style Sheets</title>
<link rel="stylesheet" type="text/css"href="default.css" />
<link rel="alternate stylesheet" type="text/css"href="red.css"
title="redstyle" />
<link rel="alternate stylesheet" type="text/css"href="green.css"
title="greenstyle" />
<link rel="alternate stylesheet" type="text/css"href="blue.css"
title="bluestyle" />
<link rel="alternate stylesheet" type="text/css"href="fonta.css"
title="fontstylea" />
<link rel="alternate stylesheet" type="text/css"href="fontb.css"
title="fontstyleb" />
<link rel="alternate stylesheet" type="text/css"href="fontc.css"
title="fontstylec" />
<script language="javascript">
function changeStyleSheet(title){
var lnks=document.getElementsByTagName("link");
if(!lnks){return};
for(var i=0;i<lnks.length;i++){
if(lnks[i].getAttribute("rel").indexOf("style")!=-1&&lnks
[i].getAttribute('title')){
lnks[i].disabled=true;
if(lnks[i].getAttribute('title')==title){
lnks[i].disabled = false;
}
}
}
}
function displayStyleLinks(){
var labels=new Array('Red','Green','Blue','Font Size 1','Font
Size 2','Font Size3');
var div=document.createElement('div');
div.setAttribute('id','linkcontainer');
for(var i=0;i<labels.length;i++){
var lnk=document.createElement('a');
lnk.setAttribute('href','#');
lnk.setAttribute('title',labels[i]);
lnk.appendChild(document.createTextNode(labels[i]));
div.appendChild(lnk);
}
document.getElementsByTagName('body')[0].appendChild(div);
}
window.onload=function(){
if(document.getElementById && document.createElement &&
document.getElementsByTagName){
// display style links on the browser
displayStyleLinks();
var link1=document.getElementsByTagName('a')[0];
if(!link1){return};
link1.onclick=function(){
changeStyleSheet('redstyle');
return false;
}
var link2=document.getElementsByTagName('a')[1];
if(!link2){return};
link2.onclick=function(){
changeStyleSheet('greenstyle');
return false;
}
var link3=document.getElementsByTagName('a')[2];
if(!link3){return};
link3.onclick=function(){
changeStyleSheet('bluestyle');
return false;
}
var link4=document.getElementsByTagName('a')[3];
if(!link4){return};
link4.onclick=function(){
changeStyleSheet('fontstylea');
return false;
}
var link5=document.getElementsByTagName('a')[4];
if(!link5){return};
link5.onclick=function(){
changeStyleSheet('fontstyleb');
return false;
}
var link6=document.getElementsByTagName('a')[5];
if(!link6){return};
link6.onclick=function(){
changeStyleSheet('fontstylec');
return false;
}
}
}
</script>
</head>
<body>
<h1>Working with multiple style sheets</h1>
<div>
<p>This is the sample content of the DIV.</p>
</div>
<div>
<p>This is the sample content of the DIV.</p>
</div>
<div>
<p>This is the sample content of the DIV.</p>
</div>
<div>
<p>This is the sample content of the DIV.</p>
</div>
</body>
</html>
All right, at this point you hopefully learned how to code a simple application that's capable of switching diverse alternate style sheets in a cross-browser way. Of course, as usual, feel free to introduce your own improvements to all the code samples shown in this article, so you can practice working with multiple style sheets.
Final thoughts
In this first tutorial of the series, I showed you how to manipulate a number of alternate style sheets with the assistance of JavaScript to change the visual appearance of a selected web document.
In the next part, things will become even more interesting. I'll be demonstrating how to use persistent style sheets to modify the visual presentation of specific elements within a web page.
Now that you know what the next part will be about, you won't want to miss it!
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