js fast inverse square root
function Q_rsqrt(number)
{
var i;
var x2, y;
const threehalfs = 1.5;
x2 = number * 0.5;
y = number;
var buf = new ArrayBuffer(4);
(new Float32Array(buf))[0] = number;
i = (new Uint32Array(buf))[0];
i = (0x5f3759df - (i >> 1));
(new Uint32Array(buf))[0] = i;
y = (new Float32Array(buf))[0];
y = y * ( threehalfs - ( x2 * y * y ) );
return y;
}