jQuery在复选框的更改和单击事件之间的区别

Question

As title suggests I want to know the difference between the change and click event of checkbox (in jQuery)

I have read down the answer to this What the difference between .click and .change on a checkbox

But, its not working for me. change fires even when I hit spaces without losing focus.

Here's a fiddle demo

Both seems to be working alike. Am I missing something here ?

Answer 1

According to the W3C, the onclick event is triggered by the keyboard for accessibility purposes:

SCR35: Making actions keyboard accessible by using the onclick event of anchors and buttons

In order to provide a better user experience for those without the use of a mouse, browsers have been developed to fire the onclick event even if the click occurs with a keyboard.

For this reason, jQuery's click event will fire even if the checkbox is clicked by using the keyboard's spacebar. change , obviously, will fire every time the checkbox's state changes.

The checkbox just happens to be the special case where change and click are interchangable, because you can't fire the change event without also triggering click .

Of course, the exception to this rule is if you were to use javascript to manually alter the checkbox, such as:

/* this would check the checkbox without firing either 'change' or 'click' */
$('#someCheckbox').prop('checked',true);

/* this would fire 'change', but not 'click'. Note, however, that this
   does not change the checkbox, as 'change()' is only the function that
   is fired when the checkbox changes, it is not the function that
   does the changing  */
$('#someCheckbox').trigger('change');

/* this would fire 'click', which by default change state of checkbox and automatically triggers 'change' */
$('#someCheckbox').trigger('click');

Here's a demonstration of these different actions: http://jsfiddle.net/jackwanders/MPTxk/1/

Hope this helps.

Answer 2

The main difference: when you click / hit space on a focused checkbox first the click event fired, with no changes. At this point you can still prevent the default action (with event.preventDefault() ) which would be to toggle the checked state of that checkbox, and fire the change event (which hasn't got default action).

In some browsers the change event will fire only after the first blur after the click .

Answer 3

I would guess that change fires when the checkbox changes (even if you don't click on it). Eg if you change the checkbox's state via some other function.

Answer 4

The difference I experienced is this:

var $check = $(':checkbox');
$checkbox.checked = true;
$checkbox.click( function() {
    alert(this.checked); // true
}).change( function() {
    alert(this.checked); // false
});

So with click the state has not yet changed, with change it has...

Answer 5

you can check or uncheck checkbox without clicking, using keyboard (tab and space bars) this goes to change statement but not to click. IMHO

Answer 6

Please let me know if this doesn't help I will remove my post:

Change : http://api.jquery.com/change/ - I reckon change event get triggered when the state of the element if changed ie not clicked but changed. Checkbox has checked and unchecked state.

Click : click event is when you click the element doesn't matter what the state of the checkbox is going to be.

like in pseudo code

if checkbox state is checked

    alert(Hulk is awesome);

if checkbox is click every time

    alert(Ironman is alright);

Answer 7

Change event fires when check box status has been changed through whatever occurrence will be happened either through pressing space when check box was focused Or Triggered change event Or clicked Where as Click event has been fired only when we clicked on check box through mouse click but at that time before click if change event has been specified then it also runs and then execute click event.

Here you can see clear script has been done on bins: http://codebins.com/codes/home/4ldqpbu