JavaScript is a kludge. It's a bag on the side of a bag. The amazing thing is that it works well enough to be useful.
In terms of your ability to use them explicitly there's asm.js, typed arrays, and various proposals like value objects for the future.
This is the reason CPU instruction set architectures are so simplistic and "low level" and don't really do things for you -- because if they did, targetting such a CPU would be a major pain with all inefficiencies due to workarounds due to funky and incompatible features.