Changing DIV visibility based on select box

问题

I have a div that I want to show only if a certain value is selected from a drop down menu ( in this case , it is custom-css )

On the fiddle ( http://jsfiddle.net/obmerk99/8xnzh/1/ ) it works ok...

jQuery(document).ready(function() {

       jQuery("#k99-custom-1").change(function () {
         jQuery("#k99-custom-1 option:selected").each(function ()
        {
            if( jQuery(this).attr("value") == "custom-css")
            {
                jQuery("#customcss").show();
            }
            else
            {
                jQuery("#customcss").hide();
            }
        });
    }).change();
});

but in the real page , the select drop down is actually generated dynamically with an "add option" button , so that certain (first) select does not exists on page load (document ready ) and I think that this is the reason that it does not work ..

see the full one here in action ( not working ) : http://jsfiddle.net/obmerk99/ZcAzy/1/

What am i doing wrong in order to have the div shown if the "custom-css" value is selected ? ( now it is set to work only with the first one ( or second ) - but it would be great to make it work with all of the added select lists .. )

回答1:

Try using delegation, like so:

jQuery(function() {
    //  Here, `.on` is used in its `delegate` form, where it asigns an event to any
    //    element matching the selector
    //    regardless when it was added to the DOM
    jQuery(document).on('change', "[id^='k99-custom-']", function(e) {
        jQuery("[id^='k99-custom-'] option:selected").each(function(i) {
            if (jQuery(this).attr("value") == "custom-css") {
                jQuery("#customcss").show();
            }
            else {
                jQuery("#customcss").hide();
            }
        });
    })
})

I just noticed in a comment on another answer, you tried something like this. What you did wrong was to delegate the event of selector [id^='k99-custom-'] to [id^='k99-custom-'], which, as you can see, is itself. To delegate, you need to asign to either a parent element or the document itself, as in my example. The most common use is simply to use $(document).on(...

Example

Learn more about .delegate and the .on form of it!

回答2:

You need to use the on function instead of just change to bind to dynamic elements.

$('body').on('change','#k99-custom-1',function(){
  //function here
});

来源：https://stackoverflow.com/questions/17434793/changing-div-visibility-based-on-select-box