ChatGPT解决这个技术问题 Extra ChatGPT

jQuery checkbox checked state changed event

I want an event to fire client side when a checkbox is checked / unchecked:

$('.checkbox').click(function() {
  if ($(this).is(':checked')) {
    // Do stuff
  }
});

Basically I want it to happen for every checkbox on the page. Is this method of firing on the click and checking the state ok?

I'm thinking there must be a cleaner jQuery way. Anyone know a solution?

@Arif I don't think they're duplicates because the linked question is about getting the state of a checkbox, while this one is about a checked event.
I always have to search for this checked property, there are many ways to achieve this as written here

c
calvin

Bind to the change event instead of click. However, you will probably still need to check whether or not the checkbox is checked:

$(".checkbox").change(function() {
    if(this.checked) {
        //Do stuff
    }
});

The main benefit of binding to the change event over the click event is that not all clicks on a checkbox will cause it to change state. If you only want to capture events that cause the checkbox to change state, you want the aptly-named change event. Redacted in comments

Also note that I've used this.checked instead of wrapping the element in a jQuery object and using jQuery methods, simply because it's shorter and faster to access the property of the DOM element directly.

Edit (see comments)

To get all checkboxes you have a couple of options. You can use the :checkbox pseudo-selector:

$(":checkbox")

Or you could use an attribute equals selector:

$("input[type='checkbox']")

Actually I've got it looking for the checkbox by the class. Is there a better way to just get all checkboxes regardless of class?
@AnonyMouse - See my edit. There are a couple of ways to do it.
@Vigrond - Actually, clicking a label does trigger the click event on the associated control: jsfiddle.net/ZFG84
This is much cleaner than $(this).is(':checked'). I thought you had to use the change event if you want to detect changes from the keyboard (tabbing, hitting space), but surprisingly, click also detects changes that aren't from a mouse click, not sure if it's a jQuery thing, jsfiddle.net/mendesjuan/E39sz
Please note: Binding any event click, change or whatever to all checkboxes on the page can cause performance issues (depepending on the amount of checkboxes). Try binding to the parent element or the document and capturing the bubbled event i.e. $('form').on('change', ':checkbox', function(){ //stuff });
F
Flimm

For future reference to anyone here having difficulty, if you are adding the checkboxes dynamically, the correct accepted answer above will not work. You'll need to leverage event delegation which allows a parent node to capture bubbled events from a specific descendant and issue a callback.

// $(<parent>).on('<event>', '<child>', callback);
$(document).on('change', '.checkbox', function() {
    if(this.checked) {
      // checkbox is checked
    }
});

Note that it's almost always unnecessary to use document for the parent selector. Instead choose a more specific parent node to prevent propagating the event up too many levels.

The example below displays how the events of dynamically added dom nodes do not trigger previously defined listeners.

$postList = $('#post-list'); $postList.find('h1').on('click', onH1Clicked); function onH1Clicked() { alert($(this).text()); } // simulate added content var title = 2; function generateRandomArticle(title) { $postList.append('

Title ' + title + '

'); } setTimeout(generateRandomArticle.bind(null, ++title), 1000); setTimeout(generateRandomArticle.bind(null, ++title), 5000); setTimeout(generateRandomArticle.bind(null, ++title), 10000);

Title 1

Title 2

While this example displays the usage of event delegation to capture events for a specific node (h1 in this case), and issue a callback for such events.

$postList = $('#post-list'); $postList.on('click', 'h1', onH1Clicked); function onH1Clicked() { alert($(this).text()); } // simulate added content var title = 2; function generateRandomArticle(title) { $postList.append('

Title ' + title + '

'); } setTimeout(generateRandomArticle.bind(null, ++title), 1000); setTimeout(generateRandomArticle.bind(null, ++title), 5000); setTimeout(generateRandomArticle.bind(null, ++title), 10000);

Title 1

Title 2


Amazing. I have just understood some more fundamentals here.
This explains "why" my click event wasn't working - thank you!!
NOTE: For parent (in above example: #post-list), you must use the element of document that is NOT being dynamically created. In my case, the div that holds the partial view.
S
Siddhartha Chowdhury

Just another solution

$('.checkbox_class').on('change', function(){ // on change of state
   if(this.checked) // if changed state is "CHECKED"
    {
        // do the magic here
    }
})

While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value.
M
Matas Vaitkevicius

If your intention is to attach event only on checked checkboxes (so it would fire when they are unchecked and checked later again) then this is what you want.

$(function() {
    $("input[type='checkbox']:checked").change(function() {

    })
})

if your intention is to attach event to all checkboxes (checked and unchecked)

$(function() {
    $("input[type='checkbox']").change(function() {

    })
})

if you want it to fire only when they are being checked (from unchecked) then @James Allardice answer above.

BTW input[type='checkbox']:checked is CSS selector.


What if you want to find only not-checked checkboxes? I have this for all checked $("#tableUSNW tbody tr td[id=td1] :checkbox:checked"); but I don't know how to find all non-checked.
@FrenkyB try following: $("input[type='checkbox']:not(:checked)")
R
Radames E. Hernandez

Is very simple, this is the way I use:

JQuery:

$(document).on('change', '[name="nameOfCheckboxes[]"]', function() {
    var checkbox = $(this), // Selected or current checkbox
        value = checkbox.val(); // Value of checkbox

    if (checkbox.is(':checked'))
    {
        console.log('checked');
    }else
    {
        console.log('not checked');
    }
});

Regards!


d
daan.desmedt
$(document).ready(function () {
    $(document).on('change', 'input[Id="chkproperty"]', function (e) {
        alert($(this).val());
    });
});

S
Shan

This is the solution to find is the checkbox is checked or not. Use the #prop() function//

$("#c_checkbox").on('change', function () {
                    if ($(this).prop('checked')) {
                        // do stuff//
                    }
                });

L
Lawrence E Bosumbe

It can also be accomplished as below. When the checkbox is fired, the div or control with #checkbox id is hiddden or is shown otherwise.

 <script>
      $('#checkbox').on('click',function(){
          if(this.checked){
              $('#checkbox').hide();
           }else{
              $('#checkbox').show();
           }
      });
 </script>

H
Hasib Kamal Chowdhury

Action taking based on an event (on click event).

$('#my_checkbox').on('click',function(){
   $('#my_div').hide();
   if(this.checked){
     $('#my_div').show();
   }
});

Without event taking action based on current state.

$('#my_div').hide();
if($('#my_checkbox').is(':checked')){
  $('#my_div').show();
}

on 'click' event doesn't work in this case. on 'change' works.
C
Caner

perhaps this may be an alternative for you.

<input name="chkproperty" onchange="($(this).prop('checked') ? $(this).val(true) : $(this).val(false))" type="checkbox" value="true" />`

N
Nɪsʜᴀɴᴛʜ ॐ

Try this jQuery validation

$(document).ready(function() { $('#myform').validate({ // initialize the plugin rules: { agree: { required: true } }, submitHandler: function(form) { alert('valid form submitted'); return false; } }); });



K
Kamil Kiełczewski

Try this "html-approach" which is acceptable for small JS projects

function msg(animal,is) { console.log(animal, is.checked); // Do stuff } Do you have a dog?
Do you have a frog?
...


S
Siwei

the key is: use prop but not attr to query the checked status, e.g.

correct: jQuery('#my_check_tag').prop('checked') // return correct status

incorrect: jQuery('#my_check_tag').attr('checked') // always return undefined