Merge PDF Files in JavaScript

readme.md

Read the complete article on how to merge two PDF files in JavaScript: https://blog.aspose.com/pdf/merge-pdf-in-javascript/

merge-pdf.js

var ffileMerge = function (e) {
  const file_reader = new FileReader();
  
  function readFile(index) {
    /*only two files*/
    if (index >= e.target.files.length || index >= 2) {
      
      /*merge two PDF-files and save the "ResultMerge.pdf"*/
      const json = AsposePdfMerge2Files(undefined, undefined, e.target.files[0].name, e.target.files[1].name, "ResultMerge.pdf");
      if (json.errorCode == 0) document.getElementById('output').textContent = json.fileNameResult;
      else document.getElementById('output').textContent = json.errorText;
      
      /*make a link to download the result file*/
      DownloadFile(json.fileNameResult, "application/pdf");
      return;
    }
    const file = e.target.files[index];
    file_reader.onload = function (event) {
      /*prepare(save) file from BLOB*/
      AsposePdfPrepare(event.target.result, file.name);
      readFile(index + 1)
    }
    file_reader.readAsArrayBuffer(file);
  }
  readFile(0);
}

/*Make a link to download the result file*/
const DownloadFile = (filename, mime, content) => {
  mime = mime || "application/octet-stream";
  var link = document.createElement("a"); 
  link.href = URL.createObjectURL(new Blob([content], {type: mime}));
  link.download = filename;
  link.innerHTML = "Click here to download the file " + filename;
  document.body.appendChild(link); 
  document.body.appendChild(document.createElement("br"));
  return filename;
}