Required library edition:
Required library file: dhtmlxgrid.js

dynamically sets colspan in row starting from specified column index

• row_id - row id
• col_id - index of column
• colspan - size of colspan

Note before using this method colspan should be enabled:

   mygrid.enableColSpan(true);
   //merge first 2 cells in the row with id "row1"
   mygrid.setColspan("row1",0,2);

See also: setRowspan, enableRowspan, enableColSpan