Joins multiple Uint8Arrays (or regular Arrays) passed as arguments into one combined Uint8Array.

joinUint8Arrays.js

function joinUint8Arrays() { 
  var args = Array.prototype.slice.call(arguments); 
  var length = args.reduce(function(a, b) { return a + b.length; }, 0); 
  var out = new Uint8Array(length);

  args.reduce(function(previousLen, buffer) {
    out.set(buffer, previousLen);
    return previousLen + buffer.length;
  }, 0);

  return out;
}