"exists" function in jQuery

For verify the existence of an element in jQuery this is the piece of code:

jQuery.fn.exists = function(){return this.length>0;}

if ($(selector).exists()) {
    // Do something
}

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Remove event handler in an element with jQuery

[2011 - jQuery 1.7 <]

With jQuery 1.7 onward the event API has been updated, .bind()/.unbind() are still available for backwards compatibility, but the preferred method is using the on()/off() functions. The below would now be,

$('#myimage').click(function() { return false; }); // Adds another click event
$('#myimage').off('click');
$('#myimage').on('click.mynamespace', function() { /* Do stuff */ });
$('#myimage').off('click.mynamespace');

In your example code you are simply adding another click event to the image, not overriding the previous one:

$('#myimage').click(function() { return false; }); // Adds another click event

Both click events will then get fired.

As people have said you can use unbind to remove all click events:

$('#myimage').unbind('click');

If you want to add a single event and then remove it (without removing any others that might have been added) then you can use event namespacing:

$('#myimage').bind('click.mynamespace', function() { /* Do stuff */ });

and to remove just your event:

$('#myimage').unbind('click.mynamespace');

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Get all the styles associated with an element jQuery

A couple years late, but here is a solution that retrieves both inline styling and external styling:

function css(a) {
    var sheets = document.styleSheets, o = {};
    for (var i in sheets) {
        var rules = sheets[i].rules || sheets[i].cssRules;
        for (var r in rules) {
            if (a.is(rules[r].selectorText)) {
                o = $.extend(o, css2json(rules[r].style), css2json(a.attr('style')));
            }
        }
    }
    return o;
}

function css2json(css) {
    var s = {};
    if (!css) return s;
    if (css instanceof CSSStyleDeclaration) {
        for (var i in css) {
            if ((css[i]).toLowerCase) {
                s[(css[i]).toLowerCase()] = (css[css[i]]);
            }
        }
    } else if (typeof css == "string") {
        css = css.split("; ");
        for (var i in css) {
            var l = css[i].split(": ");
            s[l[0].toLowerCase()] = (l[1]);
        }
    }
    return s;
}

Pass a jQuery object into css() and it will return an object, which you can then plug back into jQuery's $().css(), example:

var style = css($("#elementToGetAllCSS"));
$("#elementToPutStyleInto").css(style);

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Check the existence of an element in jQuery

jQuery.fn.exists = function(){return this.length>0;}

if ($(selector).exists()) {
    // Do something
}

This is in response to: Herding Code podcast with Jeff Atwood

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How to: detect a click outside an element with jQuery

Attach a click event to the document body which closes the window. Attach a separate click event to the window which stops propagation to the document body.

$('html').click(function() {
//Hide the menus if visible
});

$('#menucontainer').click(function(event){
    event.stopPropagation();
});

Warning, if using this technique, be aware of the dangers of stopping propagation.

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