JavaScript

Add a Related File to an HTML Email

Demonstrates the Chilkat Email.AddRelatedFile method, which adds the contents of a local file as a related MIME resource and returns the generated Content-ID. The returned value is the bare Content-ID — no angle brackets and no cid: prefix — so if it returns CID-123@example, the HTML reference is cid:CID-123@example. Because the Content-ID is generated by the call, this example adds the image first, then builds the HTML body in a StringBuilder — using a placeholder in the <img> tag that is replaced with the returned Content-ID — and passes the result to SetHtmlBody.

Background: To embed an image so it displays inside an HTML email (rather than being downloaded from a web server), you add it as a "related" part and reference it from the HTML with a cid: URL that matches the part's Content-ID. Since Chilkat assigns that ID when you add the file, the natural order is: add the related file, capture the returned ID, then build the <img src="cid:..."> reference from it. A StringBuilder makes assembling and updating the HTML convenient.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

JavaScript

//  Demonstrates the AddRelatedFile method, which adds a local file as a related MIME
//  resource (such as an image displayed by an HTML body) and returns the generated
//  Content-ID.  The HTML references the item using cid:<Content-ID>.

var email = new CkEmail();
email.Subject = "Email with a related image";

//  Add the image file as a related item first.  The return value is the bare Content-ID
//  (no angle brackets and no "cid:" prefix).
var cid = email.AddRelatedFile("qa_data/images/logo.png");
if (email.LastMethodSuccess == false) {
    console.log(email.LastErrorText);
    return true;
}

//  Build the HTML body in a StringBuilder, using a placeholder where the image's
//  Content-ID will go.
var sbHtml = new CkStringBuilder();
sbHtml.Append("<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>");

//  Replace the placeholder with the actual Content-ID returned by AddRelatedFile.
var numReplaced = sbHtml.Replace("PLACEHOLDER_CID",cid);

//  Set the HTML body from the StringBuilder result.
email.SetHtmlBody(sbHtml.GetAsString());

console.log("Related Content-ID = " + cid);
console.log("NumRelatedItems = " + email.NumRelatedItems);

//  Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
//  relative to the current working directory of the running application.