Question

I’m trying to develop a plugin that takes a callback as the first argument on init. I’ve tried to modify the plugin code from the official tutorial. I can’t figure out why what’s wrong here:

The plugin:

(function( $ ){

    var methods = {

        init : function( callback, options ) { 

            // Create some defaults, extending them with any options that were provided
            var settings = $.extend( {
                'location'         : 'top',
                'background-color' : 'blue'
                }, options);


            return this.each(function() {        

                $this.click(function(e) {

                    e.stopPropagation();
                    var $target = $(e.target);
                    if (callback) 
                        callback($target);
                });

            });
        },

    };

    $.fn.myplugin = function( method ) {

        // Method calling logic
        if ( methods[method] ) {
            return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
        } else if ( typeof method === 'object' || ! method ) {
            return methods.init.apply( this, arguments );
        } else {
            $.error( 'Method ' +  method + ' does not exist on jQuery.myplugin' );
        }

    };

})( jQuery );

Calling the plugin:

// Create callback function
var callback = function(){alert('hey');};

$('#my-control').myplugin(callback,{'width':'600px'}); 

The Error:

Method function (){alert(‘hey’);} does not exist on jQuery.myplugin

Answer 1

This line:

else if ( typeof method === 'object' || ! method ) {

Is causing the $.error condition (in the next else clause) to fire off, since you’re checking for a method name or options object and didn’t account for passing in an argument of type function.

I would recommend making the callback option part of your options object instead:

(function($) {

    var methods = {

        init: function(options) {
            console.dir(arguments);
            // Create some defaults, extending them with any options that were provided
            var settings = $.extend({
                'location': 'top',
                'background-color': 'blue'
            }, options);


            return this.each(function() {

                $(this).click(function(e) {

                    e.stopPropagation();
                    var $target = $(e.target);
                    if (settings.callback) settings.callback($target);
                });

            });
        },

    };

    $.fn.myplugin = function(method) {

        // Method calling logic
        if (methods[method]) {
            return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
        } else if (typeof method === 'object' || !method) {
            return methods.init.apply(this, arguments);
        } else {
            $.error('Method ' + method + ' does not exist on jQuery.myplugin');
        }

    };

})(jQuery);

Usage:

var callback = function(){alert('hey');};
$('#my-control').myplugin({'width':'600px', callback: callback}); 

Example: http://jsfiddle.net/n66mU/