用cookies实现的可记忆的样式切换效果代码下载_javascript技巧

red
blue

red
blue


left
right

styleswitcher.js
代码如下:
// styleswitcher.js

function setActiveStyleSheet(title)
{
var i, a, main;

for(i = 0; (a = document.getElementsByTagName("link")[i]); i++)
{
if (a.getAttribute("rel").indexOf("style") != -1 &&
a.getAttribute("title"))
{
a.disabled = true;

if (a.getAttribute("title") == title)
a.disabled = false;
}
}
}

function getActiveStyleSheet()
{
var i, a;

for(i = 0; (a = document.getElementsByTagName("link")[i]); i++)
{
if(a.getAttribute("rel").indexOf("style") != -1 &&
a.getAttribute("title") && ! a.disabled)
return a.getAttribute("title");
}

return null;
}

function getPreferredStyleSheet()
{
var i, a;

for (i = 0; (a = document.getElementsByTagName("link")[i]); i++)
{
if(a.getAttribute("rel").indexOf("style") != -1 &&
a.getAttribute("rel").indexOf("alt") == -1 &&
a.getAttribute("title"))
return a.getAttribute("title");
}

return null;
}

function createCookie(name, value, days)
{
if (days)
{
var date = new Date();
date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
var expires = "; expires=" + date.toGMTString();
}

else expires = "";
document.cookie = name + "=" + value + expires + "; path=/";
}

function readCookie(name)
{
var nameEQ = name + "=";
var ca = document.cookie.split(';');

for (var i = 0; i < ca.length; i++)
{
var c = ca[i];

while (c.charAt(0) == ' ')
c = c.substring(1, c.length);

if (c.indexOf(nameEQ) == 0)
return c.substring(nameEQ.length, c.length);
}

return null;
}

window.onload = function(e)
{
var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();

setActiveStyleSheet(title);
}

window.onunload = function(e)
{
var title = getActiveStyleSheet();

createCookie("style", title, 365);
}

var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();
setActiveStyleSheet(title);

red.css
代码如下:
#left { background-color:#0000FF; float:right;}

red.css
代码如下:
#left { background-color:#FF0000;float:left; }