I am currently working on dropdown/Select in AEM 6.5, I want to limit the number of selected options , the user must only select certain maximum number of options say 2 or 3 options and the field must be disabled unless they remove the previously selected option.
This can be done by associating "validation" property to the desired dialog field and include desired logic in JS targeting the respective "validation" property. (Need not exactly be "validation" property, it can be granite:class or granite:id. Idea is to have an identifier for the respective dialog field and write logic targeting the same.)
Field Limit can be configured at dialog field level via "granite:data" node. (Will be available as data attribute on the field and the values authored can be compared against the allowed limit)