选择多个下拉列值时启用/禁用按钮

Question

我一直在尝试使用jQuery代码在选择所有html选择下拉列表时启用按钮，或者如果没有选择单个选项则尝试禁用按钮。

这是我到目前为止所尝试的，但我的代码无法正常工作。有什么建议吗？

$(function() {
  $('.picker').on('change', function() {
    var SelectList = $('.picker');
    //Here i'll find how many dropdown are present
    for (var i = 0; i < SelectList.length; i++) {
      //Here i need to check each dropdown value whether it selected or not
      if (SelectList[i].val() != "") {
        //If all dropdown is selected then Enable button
        $("#Testing").attr("disabled", true);
      } else {
        //Disable button if any dropdown is not selected
        $("#Testing").attr("disabled", false);
      }
    }
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="button-a">A</option>
    <option value="button-b">B</option>
    <option value="button-c">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="button-a">A</option>
    <option value="button-b">B</option>
    <option value="button-c">C</option>
  </select>
</div>

<div>
  <input id="Testing" type="button" class="btn btn-info" value="Testing" />
</div>

Answer 1

无需循环 - 我也会触发更改onload以在（重新）加载时禁用：

$(function() {
  $('.picker').on('change', function() {
    var $sels = $('.picker option:selected[value=""]');
    $("#Testing").attr("disabled", $sels.length > 0);
  }).change();
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="1">A</option>
    <option value="2">B</option>
    <option value="3">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="button-a">A</option>
    <option value="button-b">B</option>
    <option value="button-c">C</option>
  </select>
</div>

<div>
  <select class="picker">
    <option value="">Select</option>
    <option value="button-a">A</option>
    <option value="button-b">B</option>
    <option value="button-c">C</option>
  </select>
</div>

<div>
  <input id="Testing" type="button" class="btn btn-info" value="Testing" />
</div>

Answer 2

使用下面的代码 SelectList [i] .value 而不是 SelectList [i] .val（）

 $(function () {
        $('.picker').on('change', function () {     
            var SelectList = $('.picker');
            //Here i'll find how many dropdown are present
            for (var i = 0; i < SelectList.length ; i++) {
                //Here i need to check each dropdown value whether it selected or not
                if (SelectList[i].value != "") {
                    //If all dropdown is selected then Enable button
                    $("#Testing").attr("disabled", true);
                }
                else {
                    //Disable button if any dropdown is not selected
                    $("#Testing").attr("disabled", false);
                }
            }
        }); 
    });