四種常用的javascript動態(tài)加載方法實現(xiàn)代碼總結

<script language="javascript"> 
document.write("<script src='test.js'><\/script>"); 
</script>

<script src='' id="s1"></script> 
<script language="javascript"> 
s1.src="test.js" 
</script>

<script> 
var oHead = document.getElementsByTagName('HEAD').item(0); 
var oScript= document.createElement("script"); 
oScript.type = "text/javascript"; 
oScript.src="test.js"; 
oHead.appendChild( oScript); 
</script>

<script language="JavaScript"> 
function GetHttpRequest() 
{ 
if ( window.XMLHttpRequest ) // Gecko 
return new XMLHttpRequest() ; 
else if ( window.ActiveXObject ) // IE 
return new ActiveXObject("MsXml2.XmlHttp") ; 
} 
function AjaxPage(sId, url){ 
var oXmlHttp = GetHttpRequest() ; 
oXmlHttp.OnReadyStateChange = function() 
{ 
if ( oXmlHttp.readyState == 4 ) 
{ 
if ( oXmlHttp.status == 200 || oXmlHttp.status == 304 ) 
{ 
IncludeJS( sId, url, oXmlHttp.responseText ); 
} 
else 
{ 
alert( 'XML request error: ' + oXmlHttp.statusText + ' (' + oXmlHttp.status + ')' ) ; 
} 
} 
} 
oXmlHttp.open('GET', url, true); 
oXmlHttp.send(null); 
} 
function IncludeJS(sId, fileUrl, source) 
{ 
if ( ( source != null ) && ( !document.getElementById( sId ) ) ){ 
var oHead = document.getElementsByTagName('HEAD').item(0); 
var oScript = document.createElement( "script" ); 
oScript.language = "javascript"; 
oScript.type = "text/javascript"; 
oScript.id = sId; 
oScript.defer = true; 
oScript.text = source; 
oHead.appendChild( oScript ); 
} 
} 
AjaxPage( "scrA", "b.js" ); 
alert( "主頁面動態(tài)加載JS腳本。"); 
alert( "主頁面動態(tài)加載a.js并取其中的變量：" + str ); 
</script>

var Rash=true; 
var msg=""; 
function norash() 
{ 
if (confirm("確定要取消嗎")) 
Rash=false; 
} 
function rashit() 
{ 
setInterval('getrss()',Inttime); 
} 
function getrss() 
{ 
if (Rash==true) 
{ 
head=document.getElementsByTagName('head').item(0); 
script=document.createElement('script'); 
script.src='INCLUDE/AutoUpdate.asp'; 
script.type='text/javascript'; 
script.defer=true; 
void(head.appendChild(script)); 
window.status=msg; 
} 
} 
rashit();