The method getcolno returns the column index of a grid cell. The argument is a grid element.
var pggrid = new jsgrid();
pggrid.init({
id:"wrp",
rows:5,
columns:12,
width:25,
height:20,
gutter:1,
backgroundColor: "#7fffd4"
});
var cols = pggrid.getcolumns(4);
var colno = pggrid.getcolno(cols[2]);
// return 4