How to update only specified column?

How to do with DHX html gantt method?

Hello Foram,
Gantt doesn’t work that way. You cannot update the data only for the specified column.
You can only repaint one row, several rows, or the whole Gantt. For that, you need to use the following methods:

If you want to modify the properties of a single column in the column configuration, you need to use the refreshData or render methods to repaint the changes.

Here are examples:

If you want to modify a specific property of all tasks, you need to manually iterate tasks and modify the property. To do that, you need to use the eachTask method:
To repaint the changes only once, you can wrap it with the batchUpdate method:
Here is an example of how it can be implemented: