function MULTIDOOR() { 
var xmlhttp; 
var pagesToDisplay = ['door.html', 'bath.html', 'patio.html', 'terrace.html']; 
if (window.XMLHttpRequest) { 
xmlhttp = new XMLHttpRequest(); 
} else { 
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); 
} 
xmlhttp.onreadystatechange = function () { 
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) { 
document.getElementById("entrance").innerHTML = xmlhttp.responseText; 
} 
} 
var randomnumber = Math.floor(Math.random() * pagesToDisplay.length); 
xmlhttp.open("GET", pagesToDisplay[randomnumber], true); 
xmlhttp.send(); 
}