CODEWITHSUNDEEP
javascriptjqueryhiddenfalse-positive
Andrew Gray
Andrew Gray

Reputation: 3790

Hidden selector always deciding that an element is visible, even when its not

One of the things I'm working on for an upcoming project is a callout/tooltip system. In theory, it's a simple little thing. You take some markup like this:

<script src='jQuery 1.10.1'></script>
<a href='#' id='callout-link'>Click Me</a>

<div id='callout-id' class='callout hidden'>
    This is my tooltip text.
</div>

/* CSS Styling... */
.callout {
     position: absolute;
     z-index: 2;
}

.hidden {
     display: none;
}

...and bind it up in JavaScript so that whenever you click some link it toggles visibility.

// ...Page Script...
var $link = $('#callout-link'),
    $callout = $('#callout-id');

$(document).ready(function () {
    var callout = new MyCallout($link, $callout);
    callout.bindToControlClick();
});

// ...Object Definition...
var MyCallout = function ($control, $callout) {
    init();

    // Public Scope...
    var pub = {};
    pub.$actionControl = $control;
    pub.$callout = $callout;

    pub.bindToControlClick = function () {
        pub.$actionControl.click(function (e) {
            e.preventDefault();
            e.stopPropagation();

            toggleCallout();                
        });
    }

    // Private Scope...
    function init() {
        // The callout-content subdiv is necessary for other operations that are
        // likely not relevant to the problem I am encountering.
        if($callout.children('.callout-content').length == 0)
            $callout.wrapInner('<div class="callout-content" />');
    }

    function toggleCallout() {
        if(pub.$callout.is(':hidden')) {
            // Show is actually more complicated than this, but that's not the problem.
            pub.$callout.show();
        } else {
            pub.$callout.hide();
        }
    }

    return pub;
};

The problem is that, while the callout is initially hidden from view, and appears on click, attempting to toggle the callout off fails. When I add a breakpoint and watch value in the Chrome debugger for $callout.is(':hidden'), even if the element is visible the watch value evaluates to true.

Based on jQuery's entry for the :hidden selector, it appears that a number of properties are being checked at any given time, which brings me to the Question: what is it in my setup that's managing to fool jQuery's :hidden selector into always believing the callout to be hidden, even when such is no longer the case?

EDIT: Since I notice a recent question of mine in the side panel, my team has since ensured that our app is running in IE9 Standards mode, so environment should not be a problem this go-round.

EDIT 2: Fiddle of the problematic code (UPDATED! Problem reproduced in full.)

Upvotes: 2

Views: 262

Answers (2)

Brewal
Brewal

Reputation: 8189

Try using hasClass instead : 

function toggleCallout() {
    if(pub.$callout.hasClass('hidden')) {
        pub.$callout.removeClass('hidden');
    } else {
        pub.$callout.addClass('hidden');
    }
}

Or even quicker with toggleClass : 

function toggleCallout() {
    pub.$callout.toggleClass('hidden');
}

Also make sure to put your MyCallout declaration before using it, otherwise you will get an error like

Uncaught TypeError: undefined is not a function

when calling 

var callout = new MyCallout($link, $callout);

The working Fiddle

Upvotes: 2

Andrew Gray
Andrew Gray

Reputation: 3790

The problem was actually a CSS problem - while my code is sane (as the jsFiddle in my OP shows), the .callout div was rendering with default dimensions of width: 0; height: 0, which causes :hidden to select the element.

All I had to do was add the following CSS to solve my problem:

.callout {
    width: 1em;
    height: 1em;
    /* ...As before... */
}

Lesson: Always inspect elements! What looks like a script error, may in fact be something else entirely.

Upvotes: 0

Related Questions