function shuffleArray() {
  var tmp       = new Array();
  var random    = 0;
  var length    = this.length;
  for(var i = 0; i < length; i++) {
    random          = Math.floor(Math.random() * length);
    tmp          = this[i]; 
    this[i]       = this[random];
    this[random]   = tmp;
  }
}

Array.prototype.shuffle = shuffleArray;

bilder = new Array("https://dswashington.org/fileadmin/new_start/starter/photo2.jpg","https://dswashington.org/fileadmin/new_start/starter/photo3.jpg", "https://dswashington.org/fileadmin/new_start/starter/photo4.jpg", "https://dswashington.org/fileadmin/new_start/starter/photo5.jpg", "https://dswashington.org/fileadmin/new_start/starter/photo6.jpg","https://dswashington.org/fileadmin/new_start/starter/photo7.jpg");
nummer = 0;
nummerarr = bilder.length-1;
bilder.shuffle();


function change() {

if(nummer > nummerarr) {
nummer = 0;
}
document.getElementById('bild').src = bilder[nummer];
nummer++;

return
}
window.setInterval("change()", 3000);



function initi(){
document.getElementById('bild').src = "https://dswashington.org/fileadmin/new_start/starter/photo2.jpg";
}

window.onLoad = initi;