Question

I’m am trying to create a jQuery plugin that will add new namespace functions to the context object(s), while maintaining full chain-ability. I’m not sure if it’s possible, but here’s an example of what I have so far:

(function ($) {
    var loadScreen = $('<div />').text('sup lol');

    $.fn.someplugin = function (args) {
        var args = args || {},
            $this = this;

        $this.append(loadScreen);

        return {
            'caption' : function (text) {
                loadScreen.text(text);
                return $this;
            }
        };
    }
})(jQuery);

This works fine if I do $(document.body).someplugin().caption('hey how\'s it going?').css('background-color', '#000');

However I also need the ability to do $(document.body).someplugin().css('background-color', '#000').caption('hey how\'s it going?');

Since .someplugin() returns it’s own object, rather than a jQuery object, it does not work as expected. I also need to be able to later on access .caption() by $(document.body). So for example if a variable is not set for the initial $(document.body).someplugin(). This means that somehow how .caption() is going to be set through $.fn.caption = function () ... just for the document.body object. This is the part which I’m not quite sure is possible. If not, then I guess I’ll have to settle for requiring that a variable to be set, to maintain plugin functions chain-ability.

Here’s an example code of what I expect:

$(document.body).someplugin().css('background-color', '#000');
$('.non-initialized').caption(); // Error, jQuery doesn't know what caption is
$(document.body).caption('done loading...');

Here’s what I’m willing to settle for if that is not possible, or just very inefficient:

var $body = $(document.body).someplugin().css('background-color', '#000');
$('.non-initialized').caption(); // Error, jQuery doesn't know what caption is
$body.caption('done loading...');

Answer 1

The be jquery-chainable, a jQuery method MUST return a jQuery object or an object that supports all jQuery methods. You simply have to decide whether you want your plugin to be chainable for other jQuery methods or whether you want it to return your own data. You can’t have both. Pick one.

In your code examples, you could just define more than one plugin method, .someplugin() and .caption(). jQuery does not have a means of implementing a jQuery plugin method that applies to one specific DOM object only. But, there is no harm in making the method available on all jQuery objects and you can only use it for the ones that it makes sense for.

I think you could use this:

(function ($) {
    var loadScreen = $('<div />').text('sup lol');

    $.fn.someplugin = function (args) {
        var args = args || {},
            $this = this;

        $this.append(loadScreen);
        return(this);
    }

    $.fn.caption = function (text) {
        loadScreen.text(text);
        return this;
    }
})(jQuery);

$(document.body).someplugin().css('background-color', '#000');
$('.non-initialized').caption('whatever');
$(document.body).caption('done loading...');

If there’s supposed to be some connection between the two .caption() calls, please explain that further because I don’t follow that from your question.