LibWeb: Implement DataTransferItemList.remove()

Author: https://github.com/tcl3
Commit: d9341adb1e
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6088
Reviewed-by: https://github.com/gmta

Libraries/LibWeb/HTML/DataTransferItemList.cpp

@@ -108,6 +108,23 @@ GC::Ptr<DataTransferItem> DataTransferItemList::add(GC::Ref<FileAPI::File> file)
     return item;
 }
 
+// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitemlist-remove
+WebIDL::ExceptionOr<void> DataTransferItemList::remove(WebIDL::UnsignedLong index)
+{
+    // 1. If the DataTransferItemList object is not in the read/write mode, throw an "InvalidStateError" DOMException.
+    if (m_data_transfer->mode() != DragDataStore::Mode::ReadWrite)
+        return WebIDL::InvalidStateError::create(realm(), "DataTransferItemList is not in read/write mode"_utf16);
+
+    // 2. If the drag data store does not contain an indexth item, then return.
+    if (index >= m_data_transfer->length())
+        return {};
+
+    // 3. Remove the indexth item from the drag data store
+    m_data_transfer->remove_item(index);
+
+    return {};
+}
+
 // https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitemlist-item
 Optional<JS::Value> DataTransferItemList::item_value(size_t index) const
 {