Bit manipulation in JavaScript is complicated by the way that it attempts to be completely type free. One of the consequences of this type free approach is that numbers are always stored as 64-bit floating point values - i.e. double precision floating point.

Yes - that's correct JavaScript doesn't have an integer type that you can make use of. When needed JavaScript will perform an internal conversion to a 32-bit value but you can't gain access directly to this integer and it is converted back to floating point format as soon as it is possible.