gistfile1.js

$.fn.nInputs = function(options) {
    var $self = this;

    options = $.extend({
        number: $self.val(),
        container: $self.parent(),
    }, options);

    var $existing = options.container.find('input');
    if ($existing.length < options.number) {
        for (var i = $existing.length; i <= options.number; i++) {
            // TODO: Sort out attributes here.
            options.container.append(options.template.clone(true));
        }
    }
    elseif ($existing.length > options.number) {
        $existing.find(':gt(' + (options.number - 1) + ')').remove();
    }
}