javascript - 如何将链接分配给数组

Question

我试图为每个数组分配链接，因此对于我的代码中的每个“主题”，我希望 Q1、Q2、Q3 和 Q4 对于不同的网页具有不同的链接。因此，当按下提交按钮时，用户将被带到到网页。 例如，用户将转到网页，单击主题，单击问题，当他们单击提交时，他们将被带到问题页面(.html 或其他页面)。

var subjects = new Array("English", "Irish", "Maths", "German", "History", "Business", "Geogrpahy");
var questions = new Array();
questions["English"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["Irish"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["Maths"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["German"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["History"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["Business"] = new Array("Q1", "Q2", "Q3", "Q4");
questions["Geogrpahy"] = new Array("Q1", "Q2", "Q3", "Q4");

function resetForm(theForm) {
  /* reset subjects */
  theForm.subjects.options[0] = new Option("Please select a subject", "");
  for (var i = 0; i < subjects.length; i++) {
    theForm.subjects.options[i + 1] = new Option(subjects[i], subjects[i]);
  }
  theForm.subjects.options[0].selected = true;
  /* reset questions */
  theForm.questions.options[0] = new Option("Please select a question", "");
  theForm.questions.options[0].selected = true;
}

function updateModels(theForm) {
  var make = theForm.subjects.options[theForm.subjects.options.selectedIndex].value;
  var newModels = questions[make];
  theForm.questions.options.length = 0;
  theForm.questions.options[0] = new Option("Please select a question", "");
  for (var i = 0; i < newModels.length; i++) {
    theForm.questions.options[i + 1] = new Option(newModels[i], newModels[i]);
  }
  theForm.questions.options[0].selected = true;
}

resetForm(document.autoSelectForm);

<form name="autoSelectForm" action="" method="post">
  <select size="1" name="subjects" onchange="updateModels(this.form)">
  </select>
  <select size="1" name="questions" onclick="">
  </select>
  <input type="submit">
</form>

Answer 1

根据您的变量和数据，为每个重写此代码 new Array("Q1", "Q2", "Q3", "Q4"); 并没有真正意义问题，因为这样做似乎多余。这可以简化为这样:

附注纯javascript对于初学者来说太方便了，使用jQuery代替从here获取jquery

HTML

// we use target="_blank" and method="get" here just to show that it works
<form id="myform" name="autoSelectForm" action="http://example.com/something.php" method="get" target="_blank">
  <select size="1" name="subjects" id="subjects"></select>
  <select size="1" name="quarters" id="quarters"></select>
  <input type="submit">
</form>

JS

var subjects = [
     {
        subject: "English", quarters: [
          {name: "Q1", link: "http://example.com/engQ1.html"}, 
          {name: "Q2", link: "http://example.com/engQ2.html"}
        ]
     },
    {
      subject: "Irish", quarters: [
        {name: "Q1", link: "http://example.com/irQ1.html"}, 
        {name: "Q2", link: "http://example.com/irQ2.html"}
      ]
    }
]

var s_subj = $('#subjects');
var s_quar = $('#quarters');

setDropdownOptions(subjects);
refreshQuarters();  // load the quarters for the first subject

    function setDropdownOptions(values){
       var str_subjects = '';
        $.each(subjects, function(i, row){
          str_subjects+= '<option>'+row.subject+'</option>'; 
        });
       s_subj.html(str_subjects);
    }

   function refreshQuarters(){
       var current_subj = s_subj.val();
        $.each(subjects, function(i, row){
             if(current_subj == subjects[i].subject){
                 var str_quarters = "";
                 // loop through the subject's quarters
                 $.each(row.quarters, function(col, obj){
                    // we use data-link in storing each individual urls
                    str_quarters += '<option data-link="'+obj.link+'">'+obj.name+'</option>';
                 });
                 s_quar.html(str_quarters);
             }
        });
   }

  // add listener when subject is changed
  s_subj.change(function(){
    refreshQuarters();
  });

  // change the form action before submitting the form
  $("#myform").submit(function(){
      // get the link from the selected quarter through data-link
      var link = $("#quarters option:selected").data("link");
     $(this).attr("action", link);
  });

演示:https://jsfiddle.net/hs3oLrns/1/