The following definition of an Array works without problems in Safari (and probably Firefox too), but triggers an (legitimate) error in Opera 9.25:

var myArray = [

 1.2,

 2.3,

 3.4,

];

The error is triggered by the superfluous comma after the last element of the Array. It may be argued for both behaviors, but I would prefer all Browsers accepting such an Array definition also since in other languages (C, Python, PHP) such a redundant comma does not cause any trouble.