jQuery：如果选择选项具有特定类，则禁用按钮

Question

I have dropdown list with collection options. When option with certain class is selected I want submit button to be disabled. This is what I've tried to do:

<form id="addToCollection">
   <select id="add_to_collection">
       <option value="1" class="highlight">1</option>
       <option value="2">1</option>
       <option value="3">3</option>
   </select>
    <input  id="add-object-to-collection"
    type="submit" value="Add" class="button"/>
</form>
<input  id="add-object-to-collection" type="submit" value="Add" class="button"/>

if($('#add_to_collection option').hasClass('highlight')) {
  $("#add-object-to-collection").prop('disabled', true);
  $("#add-object-to-collection").attr('value', 'Added');
} else {
  $("#add-object-to-collection").prop('disabled', false);
  $("#add-object-to-collection").attr('value', 'Add');
}

So here, when option 1 is selected I want button to be disabled and when other options are selected button be enabled. However here button is disabled for all options.

Answer 1

Try this

 $('#add_to_collection').on('change', function () { var $option = $('option:selected', this); var $button = $('#add-object-to-collection'); if ($option.hasClass('highlight')) { $button.prop('disabled', true).val('Added'); } else { $button.prop('disabled', false).val('Add'); } }).change(); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <form id="addToCollection"> <select id="add_to_collection"> <option value="1" class="highlight">1</option> <option value="2">1</option> <option value="3">3</option> </select> <input id="add-object-to-collection" type="submit" value="Add" class="button" /> </form> 

Answer 2

Your code is almost working. The problem in your case is that you aren't checking to see if the selected option element has a class of highlight . You could use the :selected selector in order to select the selected option element. In addition, you would also need to wrap that logic within a change event callback.

You could simplify the code to the following:

This essentially listens to the change event, and determines whether the selected option element has the class highlight . The boolean is used to disabled/enable the corresponding button.

I also chained a .change() event so that the event would be fired initially.

Example Here

$('#add_to_collection').on('change', function () {
   var hasClass = $(this).find(':selected').hasClass('highlight');
   $('#add-object-to-collection').prop('disabled', hasClass).val(hasClass ? 'Added' : 'Add');
}).change();

 $('#add_to_collection').on('change', function () { var hasClass = $(this).find(':selected').hasClass('highlight'); $('#add-object-to-collection').prop('disabled', hasClass).val(hasClass ? 'Added' : 'Add'); }).change(); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <form id="addToCollection"> <select id="add_to_collection"> <option value="1" class="highlight">1</option> <option value="2">1</option> <option value="3">3</option> </select> <input id="add-object-to-collection" type="submit" value="Add" class="button" /> </form>