The disposeOnClose property (boolean) specifies whether the internal iframe object will be reused.
DayPilot.Modal.disposeOnClosetrueIf set to true, the iframe object used to display a standalone page using DayPilot.Modal.showUrl() is removed from the DOM. If set to false, the DOM object is cached and reused on the next DayPilot.Modal.showUrl() call.
const modal = new DayPilot.Modal({
disposeOnClose: false,
// ...
});
modal.showUrl("/details.html");