var baseImagePath = '/assets/images/conference/'; // incl. trailing slash
var chooseFrom = [
 'Royal_Sonesta1.jpg',
 'Royal_Sonesta2.jpg',
 'Royal_Sonesta3.jpg',
 'Royal_Sonesta4.jpg' // note no comma after last one
];

function shuffle(a) {
   for (var i = a.length; i > 0; i--) {
       var j = Math.floor(Math.random() * i);
       var temp = a[i - 1];
       a[i - 1] = a[j];
       a[j] = temp;
   }
   return a;
}

$(function() {
     shuffle(chooseFrom);
     // create an image tag in source with id of "shuffle"
     // or change this selector
     $('#shuffle').attr('src', baseImagePath + chooseFrom[0]);
});