The autoStretchFirstLoadOnly property (boolean) specifies whether the modal dialog height should be updated on iframe content reload. If set to true, the height is updated only once.
DayPilot.Modal.autoStretchFirstLoadOnlyfalseUse this option together with DayPilot.Modal.autoStretch when the modal content is loaded in an iframe and later reloads should not trigger additional height updates.
const modal = new DayPilot.Modal({
autoStretch: true,
autoStretchFirstLoadOnly: true,
// ...
});
modal.showUrl("/dialog.html");