var filesadded="" //list of files already added

function isLoadScriptFile(filename, filetype){
	if (filesadded.indexOf("["+filename+"]")==-1){ //the file is not in the filesadded list
		filesadded+="["+filename+"]" //list of files added in the form "[filename1],[filename2],etc"
		return false;
	}
	else {
		return true;
	}
}

function loadScriptFile(filename, filetype){
	if (isLoadScriptFile(filename, filetype)){ //the file is already loaded 
		//alert("file already loaded.");
		return false;
	}
	
	if (filetype=="js"){ //if filename is a external JavaScript file
		var fileref=document.createElement('script')
		fileref.setAttribute("type","text/javascript")
		fileref.setAttribute("src", filename)
	}
	else if (filetype=="css"){ //if filename is an external CSS file
		var fileref=document.createElement("link")
		fileref.setAttribute("rel", "stylesheet")
		fileref.setAttribute("type", "text/css")
		fileref.setAttribute("href", filename)
	}
	if (typeof fileref!="undefined"){
		document.getElementsByTagName("head")[0].appendChild(fileref)
		//alert("file " + filename + " loaded successfully!");
	}
}