我標(biāo)記了第三個 console.log - “console.log(elements[i])”。在這一點(diǎn)上，elements[i] 是未定義的，但在此之前它的行為符合預(yù)期。任何想法如何/為什么會發(fā)生這種情況？function get_all_tasks_within_div(div_id) {  var options = []  var checked_options = []  var elements = document.getElementById(div_id).querySelectorAll('*');  for (i = 0; i < elements.length; i++) {    if (elements[i].getAttribute("name") == "task") {      options.push(elements[i].value)      if (elements[i].checked == true) {        checked_options.push(elements[i].value)      }    }  }  return [options, checked_options]}function create_exhibits_list(deliverable_id) {  exhibits[deliverable_id] = []  var elements = document.getElementsByName("exhibit")  //get all exibits and sort  for (i = 0; i < elements.length; i++) {    try {      console.log(elements[i])      var element_id = elements[i].id;      var exhibit_number = document.getElementById(element_id + "exhibit_number").value;      var exhibit_name = document.getElementById(element_id + "exhibit_name").value;      var responsible_party = document.getElementById(element_id + "responsible_party").value;      var deliverable_type = document.getElementById(element_id + "type").value;      var deliverable_type_options = Array.apply(null, document.getElementById(element_id + "type").options).map(function(el) {        return el.value;      });      var responsible_party_options = Array.apply(null, document.getElementById(element_id + "responsible_party").options).map(function(el) {        return el.value;      });