code: function mapNonNa(array, naValue, func) {
    var len = array.length;
    var result = allocArray(len);
    for (var i = 0; i < len; i++) {
      var value = array[i];
      result[i] = isMissing(value) ? naValue : func(value);
    }
    return result;
  }
docs: Maps the 'func' on all non-missing elements of array while immediately yielding 'naValue' instead of applying 'func' for any missing elements. The returned result will be a new array of the same length as 'array'.