Today I was working with jQuery in a JavaScript file, and jQuery kept coughing up a strange error that was puzzling.

elem.nodeName is undefined

Inspecting the backtrace in firebug led me to this line

$( 'td.qty_sel :input' ).live( 'change', ns.viewModel().qtyChange() );

Seasoned JavaScript developers will probably spot the problem immediately, but it took me some time (and a developer friend) to figure it out.

He said, “because your function is not a function reference, it’s a function call”

A few seconds and a corrected script later and it was working.

$( 'td.qty_sel :input' ).live( 'change', ns.viewModel().qtyChange );

Take away:

1. When referencing existing functions in a jQuery event handler, don’t call the function  (duh) – remove the parens (duh).

🙂