function navigate(dir) {
      if (!options.enableCellNavigation) {
        return false;
      }

      if (!activeCellNode && dir != "prev" && dir != "next") {
        return false;
      }

      if (!getEditorLock().commitCurrentEdit()) {
        return true;
      }
      setFocus();

      var tabbingDirections = {
        "up": -1,
        "down": 1,
        "left": -1,
        "right": 1,
        "prev": -1,
        "next": 1
      };
      tabbingDirection = tabbingDirections[dir];

      var stepFunctions = {
        "up": gotoUp,
        "down": gotoDown,
        "left": gotoLeft,
        "right": gotoRight,
        "prev": gotoPrev,
        "next": gotoNext
      };
      var stepFn = stepFunctions[dir];
      var pos = stepFn(activeRow, activeCell, activePosX);
      if (pos) {
        var isAddNewRow = (pos.row == getDataLength());
        scrollCellIntoView(pos.row, pos.cell, !isAddNewRow);
        setActiveCellInternal(getCellNode(pos.row, pos.cell));
        activePosX = pos.posX;
        return true;
      } else {
        setActiveCellInternal(getCellNode(activeRow, activeCell));
        return false;
      }
    }
@param {string} dir Navigation direction.
@return {boolean} Whether navigation resulted in a change of active cell.