How do I obtain the value of the boolean grid type?

I have a grid with the boolean type set up for the checkboxes, how do I read the true or false value to put it into a variable to use it

Nvm I found it, I just has to get it with myGrid.selection.getCell().row.myBooleanId

For all the operations with the data you should use the dataCollection API: JavaScript DataCollection - DataCollection Overview | DHTMLX Suite 8 Docs
In you case it will be:
JavaScript DataCollection - getItem Method | DHTMLX Suite 8 Docs