Hello, that’s quite easy to achieve.
In the header add a static checkbox and add a name/id for it:
In the table repeat region add another checkbox. Add a name to it as well.
It needs to have a dynamic value assigned - your record id:
To make the records checkboxes select/unselect when you click the header checkbox you need to use the dynamic checked attribute and make them checked when the header checkbox is checked:
so select this in the picker:
In order to add/remove items to the array when checked/unchecked you need to use the dynamic events for the records checkboxes. If your array components is called arr1 then the code you need to add to your records checkbox is:
dmx-on:updated="checked ? arr1.addUniq(id) : arr1.remove(id)"
The result:
