The eventResizePostBack() method invokes the server-side EventResize handler using a PostBack (ASP.NET WebForms only).
DayPilot.Scheduler.eventResizePostBack(e, newStart, newEnd, data)e (DayPilot.Event) - object reference
newStart (DayPilot.Date) - new event start
newEnd (DayPilot.Date) - new event end
data (object) - additional custom data
This is a legacy server-side helper for ASP.NET WebForms Scheduler integrations.
Use this method when DayPilot.Scheduler.eventResizeHandling is set to "PostBack". The optional data object lets you include custom values with the PostBack request.
dp.eventResizePostBack(e, newStart, newEnd, { source: "custom-resize" });Event Resizing [doc.daypilot.org]