(Node.js) Build a multipart/related MIME Message

Demonstrates how to construct a multipart/related MIME message containing HTML and a related JPG image.

Install Chilkat for Node.js and Electron using npm at

Chilkat npm packages for Node.js
Chilkat npm packages for Electron
on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var success;

    // Start with an empty MIME object...
    var mime = new chilkat.Mime();

    // Initialize it as multipart/related.
    mime.NewMultipartRelated();

    // Set a top-level MIME header field.
    mime.SetHeaderField("Subject","Test HTML email with JPG image.");

    // Generate a Content-ID.  This will contain random data that will allow
    // the HTML's "img" tag to reference the image part in the MIME.
    var crypt = new chilkat.Crypt2();
    crypt.EncodingMode = "hex";

    var sbContentId = new chilkat.StringBuilder();
    sbContentId.Append("part1.");
    sbContentId.Append(crypt.GenRandomBytesENC(4));
    sbContentId.Append(".");
    sbContentId.Append(crypt.GenRandomBytesENC(4));
    sbContentId.Append("@chilkatsoft.com");

    // Create the HTML body.
    var sbHtml = new chilkat.StringBuilder();
    sbHtml.Append("<html><head>\r\n");
    sbHtml.Append("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n");
    sbHtml.Append("  </head>\r\n");
    sbHtml.Append("  <body bgcolor=\"#FFFFFF\" text=\"#000000\">\r\n");
    sbHtml.Append("    <p>This is a test.&nbsp; <img src=\"cid:CONTENT_ID\" height=\"20\" width=\"20\"></p>\r\n");
    sbHtml.Append("  </body>\r\n");
    sbHtml.Append("</html>\r\n");
    var numReplacements = sbHtml.Replace("CONTENT_ID",sbContentId.GetAsString());

    // Create the HTML MIME part.
    var htmlMime = new chilkat.Mime();
    htmlMime.SetBodyFromHtml(sbHtml.GetAsString());
    htmlMime.Encoding = "8bit";
    htmlMime.Charset = "utf-8";

    // Load our JPG image from a file.
    var fac = new chilkat.FileAccess();

    jpgBytes = fac.ReadEntireFile("qa_data/jpg/starfish20.jpg");

    // Create an image/jpeg MIME part.
    var jpgMime = new chilkat.Mime();
    jpgMime.SetBodyFromBinary(jpgBytes);
    // Setting the following properties has the effect of adding
    // the Content-Type, Content-Transfer-Encoding, and Content-Disposition header fields.
    // These header fields could also be set via the SetHeaderField method, in which case
    // the values of the affected properties would be updated.
    jpgMime.ContentType = "image/jpeg";
    jpgMime.Name = "starfish20.jpg";
    jpgMime.Encoding = "base64";
    jpgMime.Disposition = "inline";
    jpgMime.Filename = "starfish20.jpg";

    var sbContentIdHdr = new chilkat.StringBuilder();
    sbContentIdHdr.Append("<CONTENT_ID>");
    numReplacements = sbContentIdHdr.Replace("CONTENT_ID",sbContentId.GetAsString());
    jpgMime.SetHeaderField("Content-ID",sbContentIdHdr.GetAsString());

    // Add both parts as children of the multipart/related
    mime.AppendPart(htmlMime);
    mime.AppendPart(jpgMime);
    console.log(mime.GetMime());

    // --------------------------------------------------------------
    // --------------------------------------------------------------
    // This example builds the following MIME message.  The boundary
    // and Content-ID strings contain random data and will be different.  

    // Content-Type: multipart/related; boundary="------------A940F1230E6F0105F03DB2CB"
    // Subject: Test HTML email with JPG image.
    // 
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: text/html; charset="utf-8"
    // Content-Transfer-Encoding: 8bit
    // 
    // <html><head>
    // <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    //   </head>
    //   <body bgcolor="#FFFFFF" text="#000000">
    //     <p>This is a test.&nbsp; <img src="cid:part1.E16AE3B4.1505C436@chilkatsoft.com" height="20" width="20"></p>
    //   </body>
    // </html>
    // 
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Transfer-Encoding: base64
    // Content-Type: image/jpeg; name="starfish20.jpg"
    // Content-Disposition: inline; filename="starfish20.jpg"
    // Content-ID: <part1.E16AE3B4.1505C436@chilkatsoft.com>
    // 
    // /9j/4AAQSkZJRgABAQEASABIAAD//gAmRmlsZSB3cml0dGVuIGJ5IEFkb2JlIFBob3Rvc2hvcD8g
    // NC4w/9sAQwAQCwwODAoQDg0OEhEQExgoGhgWFhgxIyUdKDozPTw5Mzg3QEhcTkBEV0U3OFBtUVdf
    // YmdoZz5NcXlwZHhcZWdj/9sAQwEREhIYFRgvGhovY0I4QmNjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj
    // Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj/8IAEQgAFAAUAwERAAIRAQMRAf/EABcAAAMBAAAA
    // AAAAAAAAAAAAAAIDBAX/xAAYAQADAQEAAAAAAAAAAAAAAAABAgMEAP/aAAwDAQACEAMQAAAB2kZY
    // NNEijWKddfTmLgALWH//xAAbEAACAgMBAAAAAAAAAAAAAAABAgMRAAQSE//aAAgBAQABBQL0XqN+
    // pM2aqJGMiqFFCyg7z//EABwRAAICAgMAAAAAAAAAAAAAAAERAAIQIQMSUf/aAAgBAwEBPwHqU5aq
    // Axx+y1tMQl4elj//xAAcEQEAAQUBAQAAAAAAAAAAAAABEQACEBIhA1H/2gAIAQIBAT8B3Bhqy7Zc
    // enyiwmGgDhiOzj//xAAdEAABAwUBAAAAAAAAAAAAAAABAAIREBIhIkFR/9oACAEBAAY/ArZyn+Cg
    // xtxWuJaoCnqDuin/xAAcEAABBAMBAAAAAAAAAAAAAAABABEhYRAxQVH/2gAIAQEAAT8hkEwPUUR9
    // DYfE4nxtRpIkBTsayuALIiuY/9oADAMBAAIAAwAAABDWPTsf/8QAGhEAAwADAQAAAAAAAAAAAAAA
    // AAEREDFBIf/aAAgBAwEBPxC0DVPcWm+Ce4OesrkE6bjH/8QAGBEBAQEBAQAAAAAAAAAAAAAAAREA
    // QRD/2gAIAQIBAT8QahMiOc8YgSrnTY3ELclHXn//xAAcEAEBAAIDAQEAAAAAAAAAAAABEQAhMUFx
    // EFH/2gAIAQEAAT8Qn3igmSZSj+c4N4zapMy9IjFV98wncN2iuLFsCEbDGxQkI6RO/n//2Q==
    // 
    // --------------A940F1230E6F0105F03DB2CB--
    // 

}

chilkatExample();