Based on Tim James answer and Fox32's comment, the following should check for nulls, with the assumption that two nulls are not equal.
function arrays_equal(a,b) { return !!a && !!b && !(a arrays_equal([1,2,3], [1,3,4])
false
> arrays_equal([1,2,3], [1,2,3])
true
> arrays_equal([1,3,4], [1,2,3])
false
> arrays_equal(null, [1,2,3])
false
> arrays_equal(null, null)
false
