addClass and removeClass in jQuery - not removing

问题:

I'm trying to do something very simple. Basically I have a clickable div 'hot spot', when you click that it fills the screen and displays some content. I achieved this by simply changing the class of div, removing 'spot' and adding 'grown' and there's a little CSS animation to make it grow. This works fine.

The problem is, within this div there is a close_button, which at the moment is just text. I want this to switch the classes back - i.e. remove grown and readd spot. It doesn't do this when clicked. I believe it's to do with the element not having those classes when the DOM loads, but I'm new to jQuery and don't know how to work around this.

I think there's probably a much more sensible way of doing it, could someone point me in the right direction? I'd be very grateful. I've tried using toggleClass instead to no avail.

$( document ).ready(function() {      
    $(".clickable").click(function() {  
        $(this).addClass("grown");  
        $(this).removeClass("spot");
    });   

    $(".close_button").click(function() {  
        alert (this);
        $("#spot1").removeClass("grown");  
        $("#spot1").addClass("spot");
    });   
});

UPDATE:

I am using this code now,

$( document ).ready(function() {   
    $(document).on("click", ".close_button", function () { 
        alert ("oi");
        $("#spot1").addClass("spot");
        $("#spot1").removeClass("grown");
    });  


    $(document).on("click", ".clickable", function () {
        if ($(this).hasClass("spot")){
            $(this).addClass("grown");
            $(this).removeClass("spot");
        }
    });
});

strangely the close_button function still won't add 'spot' or remove 'grown' though it will add any other classes and it will remove other classes... I added the if clause because I thought perhaps both function were being triggered at the same time, undoing each other, but it seems to make no difference

回答1:

What happens is that your close button is placed inside your .clickable div, so the click event will be triggered in both elements.

The event bubbling will make the click event propagate from the child nodes to their parents. So your .close_button callback will be executed first, and when .clickable is reached, it will toggle the classes again. As this run very fast you can't notice the two events happened.

                    / \
--------------------| |-----------------
| .clickable        | |                |
|   ----------------| |-----------     |
|   | .close_button | |          |     |
|   ------------------------------     |
|             event bubbling           |
----------------------------------------

To prevent your event from reaching .clickable, you need to add the event parameter to your callback function and then call the stopPropagation method on it.

$(".close_button").click(function (e) { 
    $("#spot1").addClass("spot");
    $("#spot1").removeClass("grown");
    e.stopPropagation();
});

Fiddle: http://jsfiddle.net/u4GCk/1/

More info about event order in general: http://www.quirksmode.org/js/events_order.html (that's where I picked that pretty ASCII art =])

回答2:

The issue is caused because of event bubbling. The first part of your code to add .grown works fine.

The second part "removing grown class" on clicking the link doesn't work as expected as both the handler for .close_button and .clickable are executed. So it removes and readd the grown class to the div.

You can avoid this by using e.stopPropagation() inside .close_button click handler to avoid the event from bubbling.

DEMO: http://jsfiddle.net/vL8DP/

Full Code

$(document).on('click', '.clickable', function () {
   $(this).addClass('grown').removeClass('spot');
}).on('click', '.close_button', function (e) {
   e.stopPropagation();
   $(this).closest('.clickable').removeClass('grown').addClass('spot');
});

回答3:

Whenever I see addClass and removeClass I think why not just use toggleClass. In this case we can remove the .clickable class to avoid event bubbling, and to avoid the event from being fired on everything we click inside of the .clickable div.

$(document).on("click", ".close_button", function () { 
    $(this).closest(".grown").toggleClass("spot grown clickable");
});  

$(document).on("click", ".clickable", function () {
    $(this).toggleClass("spot grown clickable");
}); 

I also recommend a parent wrapper for your .clickable divs instead of using the document. I am not sure how you are adding them dynamically so didn't want to assume your layout for you.

http://jsfiddle.net/bplumb/ECQg5/2/

Happy Coding :)

回答4:

I would recomend to cache the jQuery objects you use more than once. For Instance:

    $(document).on("click", ".clickable", function () {
        $(this).addClass("grown");
        $(this).removeClass("spot");
    });

would be:

    var doc = $(document);
    doc.on('click', '.clickable', function(){
       var currentClickedObject = $(this);
       currentClickedObject.addClass('grown');
       currentClickedObject.removeClass('spot');
    });

its actually more code, BUT it is muuuuuuch faster because you dont have to "walk" through the whole jQuery library in order to get the $(this) object.

回答5:

I think you're almost there. The thing is, your $(this) in the "close button" listener is not the clickable div. So you want to search it first. try to replace $(this) with $(this).closest(".clickable") . And don't forget the e.stopPropagation() as Guilherme is suggesting. that should be something like:

$( document ).ready(function() {   
    $(document).on("click", ".close_button", function () { 
        alert ("oi");
        e.stopPropagation()
        $(this).closest(".clickable").addClass("spot");
        $(this).closest(".clickable").removeClass("grown");
    });  


    $(document).on("click", ".clickable", function () {
        if ($(this).hasClass("spot")){
            $(this).addClass("grown");
            $(this).removeClass("spot");
        }
    });
});

回答6:

Try this :

$('.close-button').on('click', function(){
  $('.element').removeClass('grown');
  $('.element').addClass('spot');
});

$('.element').on('click', function(){
  $(this).removeClass('spot');
  $(this).addClass('grown');
});

I hope I understood your question.

回答7:

why not simplify it?

jquery

$('.clickable').on('click', function() {//on parent click
    $(this).removeClass('spot').addClass('grown');//use remove/add Class here because it needs to perform the same action every time, you don't want a toggle
}).children('.close_button').on('click', function(e) {//on close click
    e.stopPropagation();//stops click from triggering on parent
    $(this).parent().toggleClass('spot grown');//since this only appears when .grown is present, toggling will work great instead of add/remove Class and save some space
});

This way it's much easier to maintain.

made a fiddle: http://jsfiddle.net/filever10/3SmaV/

回答8:

Use .on()

you need event delegation as these classes are not present on DOM when DOM is ready.

$(document).on("click", ".clickable", function () {
    $(this).addClass("grown");
    $(this).removeClass("spot");
});
$(document).on("click", ".close_button", function () {  
    $("#spot1").removeClass("grown");
    $("#spot1").addClass("spot");
});  

回答9:

I think that the problem is in the nesting of the elements. Once you attach an event to the outer element the clicks on the inner elements are actually firing the same click event for the outer element. So, you actually never go to the second state. What you can do is to check the clicked element. And if it is the close button then to avoid the class changing. Here is my solution:

var element = $(".clickable");
var closeButton = element.find(".close_button");
var onElementClick = function(e) {
    if(e.target !== closeButton[0]) {
        element.removeClass("spot").addClass("grown");
        element.off("click");
        closeButton.on("click", onCloseClick);
    }
}
var onCloseClick = function() {
    element.removeClass("grown").addClass("spot");
    closeButton.off("click");
    element.on("click", onElementClick);
}
element.on("click", onElementClick);

In addition I'm adding and removing event handlers.

JSFiddle -> http://jsfiddle.net/zmw9E/1/

回答10:

I actually just resolved an issue I was having by swapping around the order that I was altering the properties in. For example I was changing the attribute first but I actually had to remove the class and add the new class before modifying the attributes. I'm not sure why it worked but it did. So something to try would be to change from $("XXXX").attr('something').removeClass( "class" ).addClass( "newClass" ) to $("XXXX").removeClass( "class" ).addClass( "newClass" ).attr('something').