Comment DEDE obtient-il l'effet tournant de page de l'article précédent et de l'article suivant ?

<script type="text/javascript" language="javascript"> 
<!-- 
document.onkeydown=nextpage; 
var prevpage=&#39;{dede:prenext get=&#39;pre&#39;/}&#39;; 
var nextpage=&#39;{dede:prenext get=&#39;next&#39;/}&#39;; 
var index_page = "index.html"; 
//var bookpage="index.html"; 
function nextpage(event) 
{ 
event = event ? event : (window.event ? window.event : null); 
//if (event.keyCode==13) location=bookpage 
if (event.keyCode==13) location=index_page 
if (event.keyCode==37) 
{ 
if (prevpage!=&#39;&#39; && prevpage!=&#39;上一篇：没有了 &#39;) 
location=prevpage; 
else 
alert(&#39;这是第一页&#39;); 
} 
if (event.keyCode==39) 
{ 
if (nextpage!=&#39;&#39; && nextpage!=&#39;下一篇：没有了 &#39;) 
location=nextpage; 
else 
alert(&#39;已经是最后一页了&#39;); 
} 
} 
//--> 
function getElement(aID) 
{ 
return (document.getElementById) ? document.getElementById(aID): document.all[aID]; 
} 
function makeRequest(url){ 
http_request=false; 
if(window.XMLHttpRequest){//Mozilla,Safari,... 
http_request=new XMLHttpRequest(); 
if(http_request.overrideMimeType){ 
http_request.overrideMimeType(&#39;text/xml&#39;); 
} 
}else if(window.ActiveXObject){//IE 
try{ 
http_request=new ActiveXObject("Msxml2.XMLHTTP"); 
}catch(e){ 
try{ 
http_request=new ActiveXObject("Microsoft.XMLHTTP"); 
}catch(e){} 
} 
} 
if(!http_request){ 
alert(&#39;Giving up:(Cannot create an XMLHTTP instance)&#39;); 
return false; 
} 
return http_request; 
} 
</script>