ZingGrid now includes the ability to group rows by specifying field indices.
An alternative to enabling row grouping is to use the [type="row-group"] column and set the [index] attribute to the field indices.
If your grid dynamically updates which indices are included in row grouping, create a row-group column. Then add or remove the [group] attribute from any <zg-column>.
ZingGrid API methods also support getting or setting the group-by attribute with the getGroupBy() and setGroupBy() methods.