jquery - Fixing this so it works if the element is not on the current page -

i found fix sticky header , works great, on of pages '.menu' class doesn't exist. i'm wondering how can adjust run if element on current page. when it's not there getting error message.

"uncaught typeerror: cannot read property 'top' of undefined" because .menu isn't there

// create clone of menu, right next original. $('.menu').addclass('original').clone().insertafter('.menu').addclass('cloned').css('position','fixed').css('top','0').css('margin-top','0').css('z-index','500').removeclass('original').hide();  scrollintervalid = setinterval(stickit, 10);   function stickit() {    var orgelementpos = $('.original').offset();   orgelementtop = orgelementpos.top;                   if ($(window).scrolltop() >= (orgelementtop)) {     // scrolled past original position; show cloned, sticky element.      // cloned element should have same left position , width original element.          orgelement = $('.original');     coordsorgelement = orgelement.offset();     leftorgelement = coordsorgelement.left;       widthorgelement = orgelement.css('width');     $('.cloned').css('left',leftorgelement+'px').css('top',0).css('width',widthorgelement).show();     $('.original').css('visibility','hidden');   } else {     // not scrolled past menu; show original menu.     $('.cloned').hide();     $('.original').css('visibility','visible');   } } 

http://codepen.io/senff/pen/aygvd

you check if .menu exists before executing stickit().

like so:

if ($('.menu').length) {     // create clone of menu, right next original.     $('.menu').addclass('original').clone().insertafter('.menu').addclass('cloned').css('position','fixed').css('top','0').css('margin-top','0').css('z-index','500').removeclass('original').hide();     $(window).scroll(function(){         stickit();     }); } 

you should replace setinterval .scroll(). it's not more elegant, might motivate optimize have.

here edited pen: codepen