[EXT.NET]GridPanel序号宽度自适应

JavaScript:

var AutoRowNumbererColumn = function () {
                var gridView = Ext.getCmp("ItemGrid").getView();
                var len = Ext.getCmp("ItemGrid").getStore().data.length;
                var text = 0;
                var N = 0;
                N = parseInt(len / 300); //扩大倍数
                for (var i = 0; i < len; i++) {
                    var cellOne = gridView.getCell(i, 0);
                    text = cellOne.textContent; //当前行
                    var oldCellOneWidth = parseInt(cellOne.style.width);
                    var newCellOnewidth = oldCellOneWidth + 5 * N;
                    gridView.getCell(i, 0).style.width = newCellOnewidth + "px";

                }

                var OldOneHeaderWidth = parseInt(gridView.getHeaderCell(1, 0).sytle.wi