Read and edit metadata of PDF documents in JavaScript using pdf-lib library. Check https://products.documentprocessing.com/metadata/javascript/pdf-lib/ for more details.

edit-metadata-of-pdf-using-pdf-lib-library.js

// Import necessary modules from 'pdf-lib'
import { PDFDocument } from 'pdf-lib';

// Import 'fs/promises' for file system operations
import fs from 'fs/promises';

// Function to set metadata of a PDF document
async function setMetadata(pdfDoc) {

  // Change the Metadata of the PDF Document
  // Set the author metadata
  pdfDoc.setAuthor("Document Processing"); 
  
  // Set the title metadata
  pdfDoc.setTitle("Test Document"); 

  // Save the modified PDF as bytes
  const modifiedPdfBytes = await pdfDoc.save(); 
  
  // Write the modified PDF bytes to a new file
  await fs.writeFile("modified-pdf.pdf", modifiedPdfBytes); 
}

// Read the PDF file as bytes
const existingpdf = await fs.readFile('documentprocessing.pdf'); 

// Load the PDF using pdf-lib
const pdfDoc = await PDFDocument.load(existingpdf); 

// Call setMetadata() to change metadata of the loaded PDF document
setMetadata(pdfDoc)
  .then(() => {
  
    // Log success message if metadata is changed successfully
    console.log('Metadata Changed Successfully'); 
    
  })
  .catch((error) => {
  
    // Log an error message if an error occurs during metadata modification
    console.error('Error: ', error); 
    
  });

read-metadata-of-pdf-document-using-pdf-lib-library.js

// Import necessary modules from 'pdf-lib'
import { PDFDocument } from 'pdf-lib';

// Import 'fs/promises' for file system operations
import fs from 'fs/promises';

async function getMetadata(pdfDoc) {

  // Get and Display the Metadata of a document
  console.log("Author: ", pdfDoc.getAuthor());
  console.log("Creator: ", pdfDoc.getCreator());
  console.log("Creation Date: ", pdfDoc.getCreationDate());
  console.log("Modification Date: ", pdfDoc.getModificationDate());
  console.log("Number of pages: ", pdfDoc.getPageCount());
  
}

// Read a PDF Document
const existingpdf = await fs.readFile('modified-pdf.pdf');
const pdfDoc = await PDFDocument.load(existingpdf);

// Call getMetadata() to fetch metadata of a function
getMetadata(pdfDoc)
  .then(() => {
  
    // Log success message if metadata is changed successfully
    console.log('Metadata Fetched Successfully');
    
  })
  .catch((error) => {
  
    // Log an error message if an error occurs during metadata modification
    console.error('Error: ', error);
    
  });

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