code: function getNumElementsFromNonIndexedArrays(arrays) {
      var key = Object.keys(arrays)[0];
      var array = arrays[key];
      if (isArrayBuffer(array)) {
        return array.numElements;
      } else {
        return array.data.length / array.numComponents;
      }
    }
docs: tries to get the number of elements from a set of arrays.