Migrating shared-operations to TS (WIP)

shared-operations/functions/createSubDocument.ts

@@ -0,0 +1,19 @@
+
+import { PDFDocument } from 'pdf-lib';
+
+export async function createSubDocument(pdfDoc: PDFDocument, pagesToExtractArray: number[]): Promise<Uint8Array> {
+    const subDocument = await PDFDocument.create();
+
+    // Check that array max number is not larger pdf pages number
+    if(Math.max(...pagesToExtractArray) >= pdfDoc.getPageCount()) {
+        throw new Error(`The PDF document only has ${pdfDoc.getPageCount()} pages and you tried to extract page ${Math.max(...pagesToExtractArray)}`);
+    }
+
+    const copiedPages = await subDocument.copyPages(pdfDoc, pagesToExtractArray);
+
+    for (let i = 0; i < copiedPages.length; i++) {
+        subDocument.addPage(copiedPages[i]);
+    }
+
+    return subDocument.save();
+}