Question: I am trying to use jQuery to dynamically enable/disable a submit button for a form.

The HTML:

```
<form id="user-add-to-group">
  <table class="group-list">
    <tbody>
      <tr>
        <th>Voornaam</th>
        <th>Achternaam</th>
        <th>S/P-nummer</th>
        <th>Email</th>
        <th>Type</th>
      </tr>
      <tr>   
        <td>Name</td>
        <td>Surname</td>
        <td>No.</td>
        <td>email@bs.com</td>
        <td>student</td>
        <td><input type="checkbox" name="user_add_to_group[]" value="75F0CE8F-4B6F-4E17-BC7B-0B06AAD84625"></td>
      </tr>
    </tbody>
  </table>
  <button disabled="disabled" type="button" id="participant_add_btn" name="participant_add_btn" class="btn btn-primary">Add</button>                            
</form>

```

And the jQuery:

```
$('table.group-list tr').on("click", function(){
  $(this).find("input[type=checkbox]").trigger('click');
    if($("#user-add-to-group input[type=checkbox]:checked").length>0){
      $("#participant_add_btn").prop("disabled","false");
    }
    else {
      $("#participant_add_btn").prop("disabled","disabled");
    }
});

```

I want to make the entire table row clickable, so the jQuery triggers a click event when the tr is clicked. This works, but I cannot seem to figure out why my button won't be enabled afterwards. I want to enable it when any checkbox within the form is checked, and disable it when none of them are.

If more info is needed, please let me know.

Answer: 
> 
> `jQuery.prop` expects value to be `Boolean`, any `string` which is not empty is considred as `true` as it is truthy value
> 
> 
> 

```js
$('table.group-list tr').on("click", function() {
  $(this).find("input[type=checkbox]").trigger('click');
  $("#participant_add_btn").prop("disabled", !$("#user-add-to-group input[type=checkbox]:checked").length);
});
```

```html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<form id="user-add-to-group">
  <table class="group-list">
    <tbody>
      <tr>
        <th>Voornaam</th>
        <th>Achternaam</th>
        <th>S/P-nummer</th>
        <th>Email</th>
        <th>Type</th>
      </tr>
      <tr>
        <td>Name</td>
        <td>Surname</td>
        <td>No.</td>
        <td>email@bs.com</td>
        <td>student</td>
        <td>
          <input type="checkbox" name="user_add_to_group[]" value="75F0CE8F-4B6F-4E17-BC7B-0B06AAD84625">
        </td>
      </tr>
    </tbody>
  </table>
  <button disabled="disabled" type="button" id="participant_add_btn" name="participant_add_btn" class="btn btn-primary">Add</button>
</form>
```
```
$('#toggle').click(function () {
//check if checkbox is checked
if ($(this).is(':checked')) {

    $('#sendNewSms').removeAttr('disabled'); //enable input

} else {
    $('#sendNewSms').attr('disabled', true); //disable input
}

```

});

[**Check here.**](http://jsfiddle.net/T6hvz/)