Export specific number of pages into XFDF

I use the following code to save only page2, page4 and page6 (3 pages in total) into XFDF, but the problem its saving pages from page2 to page6 (6 pages in total), any help please in relation?

Thanks a lot
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var emptyFields = [];
var selectedPages = [2, 4, 6]; // Specify the page numbers you want to save

for (var i = 0; i < this.numFields; i++) {
var f = this.getField(this.getNthFieldName(i));

if (f.type !== "button" && f.required) {
if (f.valueAsString === f.defaultValue) {
emptyFields.push(f.name);
}
}
}

if (emptyFields.length > 0) {
app.alert("Please complete the following fields:\n" + emptyFields.join("\n"));
} else {
var newDoc = this.extractPages({
nStart: selectedPages[0] - 1, // Page numbers are 0-based index
nEnd: selectedPages[selectedPages.length - 1] - 1
});
newDoc.exportAsXFDF(); // Export only the selected pages
}