I get an error (below) when I try to run the following code (https://jsfiddle.net/o40dbvpx/1/) within my app.  This is within a SP2013 solution and jQuery is loaded (as I can show alerts).  I have tried jQuery 1.11.1 and 2.1.3.

0x800a139e - JavaScript runtime error: Syntax error, unrecognized expression: table.class=ms-formtable tr: nth-child(9)

Everything runs fine within the JSFiddle so I am sure I am hitting the correct location, but jQuery is now happy about something!

TIA!