function getElementsByClassName(className) {
        var allObj, retObj = new Array(), j=0;
        allObj = document.getElementsByTagName ? document.getElementsByTagName("*") : document.all ? document.all : 0;
        if(allObj!=0)
                for(i=0; i<allObj.length; i++)
                        if(allObj[i].className==className)
                                retObj[j++]=allObj[i];
        return retObj;
}



function arrayContains( hay, needle)
{
	var i;
	for (i=0; i<hay.length; i++)
	{
		if ( hay[i] == needle )
			return true;
	}
	return false;
}

function hideAndShow( selector )
{	
	var i;
	var option = selector.value;
	var filterArray = new Array();
	var string = new String();

	if ( option != 2 )
		filterArray = filterArray.concat( new Array('phd_thesis', 'phd_date_finish') );

	classArray = getElementsByClassName( 'filter' );
	
	for ( i=0; i<classArray.length; i++ )
	{
		string = string + ", " + classArray[i].id;
		if ( arrayContains( filterArray, classArray[i].id ) )
			string = string + "[filtered]";
	}

	for ( i=0; i<classArray.length; i++ )
	{
			
		if ( arrayContains( filterArray, classArray[i].id ) )
			classArray[i].style.display='none';
		else
			classArray[i].style.display='';
	}
	
	return;
}