Javascript - Cannot Read Property 'top' Of Null

I have function that scrolls to a anchor position in a list function snapToAnchor(anchor) { $('#divProductScroll').scrollTop(0); var offset = $(anchor).offset().top - $(

Solution 1:

The anchor variable does not contain a valid selector for you site. Calling offset on this will return null.

Example

var a = $('#non-existing-id'); //returns empty objectvar b = a.offset(); // returns null
b.top; //throws a TypeError exception

You can simply debug your program by inserting alert(anchor) on line 3. This will show you the contents of the variable.

Solution 2:

if anchor has id of the DOM element - then correct way to use it with jQuery:

$('#' + anchor).offset()

otherwise you'll get a null (and error).

Solution 3:

$(anchor).offset().top

will usually output a string not a number... something like 100px. you need to extract the number from the string.

var topoffset = $(anchor).offset().top;
topoffset = topoffset.split('px', 1);