function setActiveStyleSheet(title) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {   /*a是所有的link元素*/
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {/*检查1.是不是样式表2.有没有title*/
      a.disabled = true;/*如果有title就禁用*/
      if(a.getAttribute("title") == title) a.disabled = false;/*如果等于当前设置的title，则激活*/
    }
  }
}
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");
	/*a是所有的link元素，如果a是style并且有title，没有被禁用，则判定其为当前活跃样式，返回它的title*/
  }
  return null;
}

function getPreferredStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1/*是样式表*/
       && a.getAttribute("rel").indexOf("alt") == -1/*不是替代样式表*/
       && a.getAttribute("title")/*有title*/
       ) return a.getAttribute("title");/*满足以上三个条件，返回title*/
  }
  return null;
}
/*以下为设置cookie的函数，不研究*/
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;
}
/*以上为设置cookie的函数，不研究*/


window.onload = function(e) {
  var cookie = readCookie("style");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
}
/*读取style的cookie，如果有cookie则title=cookie，否则执行getPreferredStyleSheet()函数。最后根据title设置文档当前样式。*/


window.onunload = function(e) {
  var title = getActiveStyleSheet();
  createCookie("style", title, 365);
}

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

/*JS for the navigation of the header*/
navHover = function() {
	var lis = document.getElementById("mainNav").getElementsByTagName("LI");
	for (var i=0; i<lis.length; i++) {
		lis[i].onmouseover=function() {
			this.className+=" iehover";
		}
		lis[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" iehover\\b"), "");
		}
	}
}
if (window.attachEvent) window.attachEvent("onload", navHover);

/*To change the font size of the content area.*/
function changeFont(a){
	size = a + "px";
	document.getElementById("content").style.fontSize = size;
}
function showresult() {
	 var doc = window.frames["resultiframe"].document;
    var src = document.getElementById("srctext");
    doc.write(src.value);
    doc.close();
    doc.createAttribute("charset", "UTF-8");
}