Addressing neopixel via Uint24Array()

There isn't anything I'm aware of. Ideally we'd need a new function that allows Espruino's interpreting of those {data,count} blocks to work on existing buffers, but that doesn't exist yet.

Best bet on official boards is to use JIT:

var countNP = 100;
var neopixelStrip = new Uint24Array(countNP);
var fiveLEDs = new Uint24Array(5);
fiveLEDs[2] = 30;

function repeatPattern(strip, pattern, count) { "jit"
  for (var i=0;i<count;i+=5) strip.set(pattern,i);
}

repeatPattern(neopixelStrip, fiveLEDs, countNP);