How to clear dialog/xmlfragment content after close?

Question

My dialog is defined as document:

  onOpenDialog : function () {
     var oView = this.getView();
     var oDialog = oView.byId(\"helloDialog\");
     // create         


        

Answer 1

Dialog XML

Create the Dialog

if(!this._oDialog){
    this._oDialog = sap.ui.xmlfragment("idFragment","Path_to_your_Dialog", this);           
}

You need to use destroy() of the sap.ui.core.Element.

dialogAfterclose: function(oEvent) {
    this._oDialog.destroy();
}

As per your code

onOpenDialog : function () {
  var oView = this.getView();
  if (!this._oDialog) {
      this._oDialog = sap.ui.xmlfragment(oView.getId(), "sap.ui.demo.wt.view.HelloDialog");
      oView.addDependent(this._oDialog);
  }
  this._oDialog.open();
},     
dialogAfterclose: function(oEvent) {//function called after Dialog is closed
   this._oDialog.destroy();//destroy only the content inside the Dialog
},
confirmOk: function(oEvent) {
    this._oDialog.close();//Just close the Dialog, Dialog afterClose() will be called and destroy the Dialog content.
}

Ref: sap.ui.core.Element - destroy()