Using inline object notation with numerical properties throws an error in IE Mac:
var foo = {7:'pass'};
To make matters worse, it treats it as a syntax error and ignores the entire script, and may show a warning dialog, so you cannot use try...catch to avoid this bug (unless you put it inside an eval statement).
Use numerical string instead of numbers: '7' (in most cases, this is equivalent to using numbers, although strings like '007' will produce the wrong result), or use normal property notation:
var foo = {'7':'pass'};
foo.3 = 'another pass';