Animated text in jquery

jquery-animated-text.js

(function ( $ ) {

     $.fn.animatedText = function (first_param, options) {

        var $self = $(this);

        $self.attr('in-animation-text', 'true');

        if ($.isPlainObject(first_param)) {

            options = first_param;

        } else if (typeof(first_param) == 'string') {

            text = first_param;

            delete first_param;

        } else if (first_param === false) {

            $self.attr('in-animation-text', 'false');

            $self.dequeue().stop().clearQueue();

            return this;
        }   


        options = options || {};

        if (! $.isPlainObject(options)) {

            throw new Error('O parâmetro deve ser um objecto');
        }


        options.delay = options.delay || 400;

        var index = 0;

        var animatedText = function() {

            var $self = $(this);

            var currentText = '';

            $self.filter('[in-animation-text=true]').delay(options.delay).queue(function (next) {

                var isValid = text.charAt(index++);

                if (isValid !== '') {

                    if (typeof(options.prefix) === 'string') {

                        currentText = options.prefix;
                    }

                    currentText += text.substr(0, index)

                    $self.html(currentText);

                    next();
                }

                if (options.infinity === true && index === text.length) {

                    index = 0;
                }


                $.proxy(animatedText, this)();

            });

        }

        $.proxy(animatedText, this)()

        return this;
    }
    
})( jQuery );