How to Remove Pages from a PDF in JavaScript (pdf-lib Tutorial)

To remove pages from pdf javascript developers can build 100% client-side web applications using the MIT-licensed pdf-lib package. By loading the binary buffer into a PDFDocument, sorting the target indices in descending order, and calling pdfDoc.removePage(index), you can manipulate documents directly inside the user’s browser without transmitting a single byte over the network.

Step 1: Install the Dependency

Step 2: TypeScript Production Implementation

Below is the exact core logic pattern employed inside PageRemover:

import { PDFDocument } from 'pdf-lib';

export async function removePagesFromPdf(
  pdfBytes: Uint8Array,
  pagesToRemove0Based: number[]
): Promise<Uint8Array> {
  // 1. Load the binary document into memory
  const pdfDoc = await PDFDocument.load(pdfBytes, { ignoreEncryption: true });
  const totalPages = pdfDoc.getPageCount();

  // 2. Validate that user is not attempting to delete all pages
  if (pagesToRemove0Based.length >= totalPages) {
    throw new Error('Cannot delete all pages from the document.');
  }

  // 3. CRITICAL: Sort indices in descending order!
  // Removing page 2 shifts old page 4 into index 3.
  // Descending order prevents index corruption.
  const sortedDescending = [...new Set(pagesToRemove0Based)].sort((a, b) => b - a);

  for (const index of sortedDescending) {
    if (index >= 0 && index < totalPages) {
      pdfDoc.removePage(index);
    }
  }

  // 4. Save and return modified binary bytes
  return await pdfDoc.save();
}

The Descending Index Gotcha (Why Order Matters)

The most common rookie mistake when pruning pages in a loop is deleting in ascending order:

Suppose you want to remove Page 1 (index 0) and Page 3 (index 2) from a 5-page document. If you delete index 0 first, all subsequent pages shift to the left: what was originally Page 3 now occupies index 1! If you then delete index 2, you accidentally delete what was originally Page 4!

By sorting your deletion targets in descending order (highest index to lowest), the indices of earlier pages remain completely unchanged as deletions occur.

Frequently Asked Questions