Quelque chose

var store_exec = new Array();

//store[0] = new Array();
store_exec[1] = new Array(<?php echo return_array_JS_us_groupes(); ?>);
store_exec[2] = new Array(<?php echo return_array_JS_users(); ?>);



function init_exec(formul, firBox, secBox) {
  var box = formul.elements[firBox]
  var i = box.options[box.selectedIndex].value;
  //document.write(i);
  if(box.options[box.selectedIndex].value == "0") {
    //optionTest = true;
    lgth = formul.elements[secBox].options.length;
    formul.elements[secBox].options[lgth] = null;
    if(formul.elements[secBox].options[lgth]) optionTest = false;
  } else {
    populate_exec(formul, firBox, secBox);
  }
}

function populate_exec(formul, firBox, secBox) {
  //if (!optionTest) return;
  var box = formul.elements[firBox];
  var number = box.options[box.selectedIndex].value;
  if (!number) return;
  var list = store_exec[number];
  var box2 = formul.elements[secBox];
  box2.options.length = 0;
  for(i=0;i<list.length;i+=2) {
    box2.options[i/2] = new Option(list[i],list[i+1]);
  }
}