missing + sign causes javascript interpreter to go haywire -

on several occasions, i've encountered situation missing character causes javascript interpreter go haywire or give useless error message. example, following 2 files differ in 2 characters (there's missing plus sign in second file):

http://phillipmfeldman.org/english/hangman.html

http://phillipmfeldman.org/english/test.html

tracking such things down can huge pain. there way debug such things?

your error line is:

elem.value= score + ' (' + points_received_sum.tofixed(2) + '/' +     points_possible_sum ')'; 

the error in console on chrome says

uncaught syntaxerror: unexpected string test.html:737 

that's clear error. it's not haywire, it's helpful error message telling problem is. there's nothing more parser / runtime you.