CODEWITHSUNDEEP
javascriptjquery
GeraldIstar
GeraldIstar

Reputation: 378

JQuery selectors missunderstanding

I'm trying to make a simple tree-view script, and start with opening/closing nodes. But I stuck with some problem: 

$(function() {

    $('#tree li.closedNode').on('click',function(e){
        e.stopPropagation();
        $(this).removeClass('closedNode').addClass('openedNode').children(':not(a.caption)').show();

    })  

    $('#tree li.openedNode').on('click',function(e){
        e.stopPropagation();

        $(this).addClass('closedNode').removeClass('openedNode').children(':not(a.caption)').hide();
    })

jsfiddle: http://jsfiddle.net/F33dS/14/

So, then you click on 'click here' it's closing, changing class, but it still firing event for 'li.openedNode'. I know, that I missed somthing simple, but what? I really can't find the problem. So, why it's working in this way?

Upvotes: 0

Views: 59

Answers (1)

Popnoodles
Popnoodles

Reputation: 28409

You're binding event to things that don't exist yet.

You need to use .on() such that it targets all matching elements whether they exist now or in the future.

http://jsfiddle.net/F33dS/16/

$('#tree').on('click', 'li.closedNode', function(e){
    e.stopPropagation();
    $(this).removeClass('closedNode').addClass('openedNode').children(':not(a.caption)').show();
})  

$('#tree').on('click', 'li.openedNode', function(e){
    e.stopPropagation();
    $(this).addClass('closedNode').removeClass('openedNode').children(':not(a.caption)').hide();
})

Your nodes have the class openNode on page load.

The script looks for $('#tree li.openNode') and matches elements.

The script looks for $('#tree li.closedNode') and matches none.

It's only when the user clicks the element that a match would be found for $('#tree li.closedNode').

So we tell its parent which exists to look for the click event for both matching descendants. As soon as one MATCHING descendant pops into existence (when you change the class name), the event triggers.

From http://api.jquery.com/on/

Event handlers are bound only to the currently selected elements; they must exist on the page at the time your code makes the call to .on(). To ensure the elements are present and can be selected, perform event binding inside a document ready handler for elements that are in the HTML markup on the page. If new HTML is being injected into the page, select the elements and attach event handlers after the new HTML is placed into the page. Or, use delegated events to attach an event handler, as described next.

Delegated events have the advantage that they can process events from descendant elements that are added to the document at a later time. By picking an element that is guaranteed to be present at the time the delegated event handler is attached, you can use delegated events to avoid the need to frequently attach and remove event handlers.

In your original code you set up the correct selector, but there were no matches at that time. So, #tree which exists at the time, can store the events made on its descendants.

Just one other thing

Why hide and show the list elements with jQuery? You're adding a class anyway so you could do that with CSS.

Upvotes: 2

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