Removing duplicate values from cascading dropdown

Question

I have multi select cascading in list newform.aspx, like in the picture below. I have values in my column, it is not shown in the picture below.

Duplicate values also come in my second column. I have code to remove duplicates from this column.

var usedNames = {};
$("select[title='TitleColumn'] > option").each(function () {
    if(usedNames[this.text]) {
        $(this).remove();
    } else {
        usedNames[this.text] = this.value;
    }
});

I wanted to know what event should I execute this code so that when items are selected in the first column and when the second column gets populated, it should only show unique values.

Answer 1

Duplicates can also be removed when cascading is done like in below cascading code we can call a function to remove duplicate.

$().SPServices.SPCascadeDropdowns({
  relationshipWebURL: "",
  relationshipList: "",
  relationshipListParentColumn: "",
  relationshipListChildColumn: "",
  relationshipListSortColumn: "",
  parentColumn: "",
  childColumn: "",
  CAMLQuery: "",
  CAMLQueryOptions: "<QueryOptions><IncludeMandatoryColumns>FALSE</IncludeMandatoryColumns></QueryOptions>", // Added in 2013.01
  listName: $().SPServices.SPListNameFromUrl(),
  promptText: "",
  simpleChild: false,           
  selectSingleOption: false,    
  matchOnId: false,             
  completefunc: RemoveDuplicate,
  debug: false
});


function RemoveDuplicate()
{
var usedNames = {};
$("select[title='Title possible values'] > option").each(function () {
        if(usedNames[this.text]) {
            $(this).remove();
        } else {
        usedNames[this.text] = this.value;
        }
    });
}