I suppose it up to the new way of change-detection on the latest version.
If you will update your code like that:
function updateColDef()
{
let data = [];
columnDefs.forEach(function(colDef) {
colDef.headerName = colDef.headerName + ' X ';
data.push(colDef);
})
data.push( {
headerName: 'New Column',
});
gridOptions.api.setColumnDefs(data);
}
It will work as expected.
Update:
When new columns are set, the grid will compare with current columns and work out which columns are old (to be removed), new (new columns created) or kept (columns that remain will keep their state including position, filter and sort).
Comparison of column definitions is done on 1) object reference comparison and 2) column ID eg colDef.colId. If either the object reference matches, or the column ID matches, then the grid treats the columns as the same column.
In the first case, it was an object comparison, on the second sample (after update) its colId
case.
changes came from 19.1 version release
AG-1591 Allow Delta Changes to Column Definitions.