> Is there a javascript function (or postback event) that I can use for this feature?
EventMoving event (https://doc.daypilot.org/scheduler/event-moving-customization/) is a good way to implement it. Just set
args.allowed = false;
if you want to forbid the current position. You can also display a label with more details:
args.right.enabled = true;
args.right.html = "This position is not allowed because .... ";
> Is possible to check in this event if the start (or end) property is business or not?
You can get this information using the cells API:
dp.cells.find("2016-04-03", "A")[0].properties.business