Add digital signature or digitally sign PDF in JavaScript via C++

A digital signature in a PDF document is a way to verify the document’s authenticity and integrity. This is the process of the electronic signature of a PDF document using a private key and digital certificate. This signature guarantees the holder that the document has not been altered or altered since the signing and that the signatory is the one whom it approves. To sign PDF with JavaScript, use the Aspose.PDF tool.

Aspose.PDF for JavaScript via C++ supports the feature to digitally sign the PDF files using the AsposePdfSignPKCS7.

Sign PDF with digital signatures

    /*Set the default PKCS7 key filename*/
    var fileSign = "/test.pfx";

    var ffileSign = function (e) {
      const file_reader = new FileReader();
      /*Set the PKCS7 key filename*/
      fileImage = e.target.files[0].name;
      file_reader.onload = (event) => {
        /*Save the BLOB in the Memory FS for processing*/
        AsposePdfPrepare(event.target.result, fileSign);
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

    /*Set the default image (Signature Appearance) filename*/
    var signatureAppearance = "/Aspose.jpg";

    var ffileImage = function (e) {
      const file_reader = new FileReader();
      /*Set the image filename*/
      signatureAppearance = e.target.files[0].name;
      file_reader.onload = (event) => {
        /*Save the BLOB in the Memory FS for processing*/
        AsposePdfPrepare(event.target.result, signatureAppearance);
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

    var ffileSignPKCS7 = function (e) {
      const file_reader = new FileReader();
      file_reader.onload = (event) => {
        let pswSign = document.getElementById("passwordSign").value;
        /*Sign a PDF-file with digital signatures and save the "ResultSignPKCS7.pdf"*/
        const json = AsposePdfSignPKCS7(event.target.result, e.target.files[0].name, 1, fileSign, pswSign, 200, 200, 200, 100, "TEST", "[e-mail]", "EU", 1, signatureAppearance,"ResultSignPKCS7.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");
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

Using Web Workers

    /*Create Web Worker*/
    const AsposePDFWebWorker = new Worker("AsposePDFforJS.js");
    AsposePDFWebWorker.onerror = evt => console.log(`Error from Web Worker: ${evt.message}`);
    AsposePDFWebWorker.onmessage = evt => document.getElementById('output').textContent = 
      (evt.data == 'ready') ? 'loaded!' :
        (evt.data.json.errorCode == 0) ?
          `Result:\n${(evt.data.operation == 'AsposePdfPrepare') ?
            'file prepared!':
            DownloadFile(evt.data.json.fileNameResult, "application/pdf", evt.data.params[0])}` :
          `Error: ${evt.data.json.errorText}`;

    /*Set the default PKCS7 key filename*/
    var fileSign = "test.pfx";
    /*Set the default image (Signature Appearance) filename: 'Aspose.jpg' already loaded, see settings in 'settings.json'*/
    var signatureAppearance = "Aspose.jpg";

    /*Event handler*/
    const ffileSignPKCS7 = e => {
      const file_reader = new FileReader();
      file_reader.onload = event => {
        const pageNum = 1;
        const pswSign = document.getElementById("passwordSign").value;
        const setXIndent = 100;
        const setYIndent = 100;
        const setHeight = 200;
        const setWidth = 100;
        const reason = 'Reason';
        const contact = '[e-mail]';
        const location = 'Location';
        const isVisible = 1;
        /*Sign a PDF-file with digital signatures and save the "ResultSignPKCS7.pdf" - Ask Web Worker*/
        AsposePDFWebWorker.postMessage(
          { "operation": 'AsposePdfSignPKCS7',
            "params": [event.target.result, e.target.files[0].name, pageNum, fileSign, pswSign, setXIndent, setYIndent,
                      setHeight, setWidth, reason, contact, location, isVisible, signatureAppearance, "ResultSignPKCS7.pdf"] },
          [event.target.result]
        );
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

    const ffileSign = e => {
      const file_reader = new FileReader();
      /*Set the PKCS7 key filename*/
      fileSign = e.target.files[0].name;
      file_reader.onload = event => {
        /*Save the BLOB in the Memory FS for processing*/
        AsposePDFWebWorker.postMessage(
          { "operation": 'AsposePdfPrepare', "params": [event.target.result, fileSign] },
          [event.target.result]
        );
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

    const ffileImage = e => {
      const file_reader = new FileReader();
      /*Set the image filename*/
      signatureAppearance = e.target.files[0].name;
      file_reader.onload = event => {
        /*Save the BLOB in the Memory FS for processing*/
        AsposePDFWebWorker.postMessage(
          { "operation": 'AsposePdfPrepare', "params": [event.target.result, signatureAppearance] },
          [event.target.result]
        );
      };
      file_reader.readAsArrayBuffer(e.target.files[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;
      }