pdf-lib save pdf yo server

how to save the pdf to the server ?? I want to save it to /pdf folder on the server I don't know how to convert "pdfBytes" and save it
someone know a solution

<html>
  <head>
    <meta charset="utf-8" />
    <script src="https://unpkg.com/pdf-lib@1.4.0"></script>
    <script src="https://unpkg.com/downloadjs@1.4.7"></script>
  </head>

  <body>
    <p>Click the button to create a new PDF document with <code>pdf-lib</code></p>
    <button onclick="createPdf()">Create PDF</button>
    <p class="small">(Your browser will download the resulting file)</p>
  </body>

  <script>
    const { PDFDocument, StandardFonts, rgb } = PDFLib

    async function createPdf() {
      // Create a new PDFDocument
      const pdfDoc = await PDFDocument.create()

      // Embed the Times Roman font
      const timesRomanFont = await pdfDoc.embedFont(StandardFonts.TimesRoman)

      // Add a blank page to the document
      const page = pdfDoc.addPage()

      // Get the width and height of the page
      const { width, height } = page.getSize()

      // Draw a string of text toward the top of the page
      const fontSize = 30
      page.drawText('Creating PDFs in JavaScript is awesome!', {
        x: 50,
        y: height - 4 * fontSize,
        size: fontSize,
        font: timesRomanFont,
        color: rgb(0, 0.53, 0.71),
      })

      // Serialize the PDFDocument to bytes (a Uint8Array)
      const pdfBytes = await pdfDoc.save()

            // Trigger the browser to download the PDF document
      download(pdfBytes, "pdf-lib_creation_example.pdf", "application/pdf");
    }
  </script>
</html>

this is the simple code ists open a file download to local pc and I ned to save it in the server in pure js