It has been proposed to ECMA:
http://wiki.ecmascript.org/doku.php?id=strawman:typed_arraysBut, since the proposal is newer than 2010, it hadn't made it into ECMA v5, which is used by Jurassic. So it doesn't work.
V8 has it since the internet is kinda their motivation.
It looks good for being in ECMA 6 though. I can, however, implement the API in my engine, it shouldn't be too hard, and would make reading Sphere binary files like map, tileset, and spritests easier to read in (with JS, that is).
Edit:
Actually, I can't modify Jurassic to do that. I would need access to the [] operator (not the C# overload, but the JS one), which means adding to and modifying the parser so that a new Array type, the TypedArray, has the ability to get and set bits of an underlying buffer with the [] operator.
Because doing this in JS, is not possible:
var buffer = new ArrayBuffer(100); // 00000000 ... 0000
var intarray = new Int32Array(buffer);
intarray[0] = 5;
buffer.toBinary() != 00000000 ... 0101
// there would need to be:
buffer.update(intarray); // but this is not a spec.
(Which is probably another reason why it is not standard).
Anyways, I'll attach the A* code. Put both into a test game folder, and try it out, using pathtest as the parent script. Use the left mouse button to create obstructions. F1 ... F6 loads maps, Shift + F1 ... F6 saves maps (for fun, testing etc), then use the right mouse button to set the two pathing nodes (you have to click a place for each node before it paves again). It is quite robust. It has 6 presets, three for speed (so you might not get shortest path, but a fast performance), and 3 accurate ones (shortest path, but slow). I'd use the first 3 for movement depending on how you want movement to work in your game (diagonal vs. tiled), and the bottom 3 for... academics.
The A* algorithm under the newer speed model, has these speeds in the Sphere Engines: (64*64 worst case)
SSFML: 36ms - old: 33
Sphere 1.6: 67ms - old: 80
Sphere 1.5: 104ms - old: 140
So, these are faster than earlier indeed, it might seem slower (36 v 33), but I found a worse worst case: not finding it's target. xD