wijmo 判断当前cell是不是groupHeader

 theGrid.formatItem.addHandler(function (s, e) {

                if (e.panel == s.cells && e.col === 0 && !(s.rows[e.row] instanceof wj.grid.GroupRow)) {
                    var html = _printUser(0,0);
                    
                    e.cell.innerHTML = html;
                }
            });

s.rows[e.row] instanceof wjGrid.GroupRow 就可以判断出来

https://demo.grapecity.com.cn/wijmo/demos/Grid/Aggregation/Customaggregation/purejs