var chemin = "img/";
var ext = ".gif";
var listimg = new Array('fond1','fond2','fond3','fond4','fond5');
document.fond = new Array();
function loadimg() {
  for(x = 0; x < 4; x++ ) {
    document.fond[x] = new Image;
    document.fond[x].src = chemin + listimg[x] + ext;
  }
}
loadimg();