JavaScript

Get the Content-ID of a Related Item

Demonstrates the Chilkat Email.GetRelatedContentID method, which returns the Content-ID of a related item (typically an image or style sheet embedded within an HTML email). The index is zero-based. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads that Content-ID back.

Background: The Content-ID is the anchor that ties an inline resource to the HTML that displays it: the body references cid: plus the ID, and the matching related part carries that same Content-ID. Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd. Reading the Content-ID back lets a program verify or rewrite those links — for example when relocating embedded images or converting a message for display outside a mail client.

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

var success = false;

//  Demonstrates the GetRelatedContentID method, which returns the Content-ID of a related
//  item.  Related items are typically images and style sheets embedded within HTML emails.
//  The index is zero-based.

var email = new CkEmail();
email.Subject = "GetRelatedContentID example";

//  Load the image data from a file into a BinData object.
var bdImage = new CkBinData();
success = bdImage.LoadFile("qa_data/images/logo.png");
if (success == false) {
    console.log(bdImage.LastErrorText);
    return true;
}

//  Add the image as a related item from the BinData; capture its generated Content-ID.
var cid = email.AddRelatedBd("logo.png",bdImage);
if (email.LastMethodSuccess == false) {
    console.log(email.LastErrorText);
    return true;
}

//  Reference the related item in the HTML body by its Content-ID.
var sbHtml = new CkStringBuilder();
sbHtml.Append("<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>");
var numReplaced = sbHtml.Replace("PLACEHOLDER_CID",cid);
email.SetHtmlBody(sbHtml.GetAsString());

//  Read the Content-ID of the first related item (index 0).
var cid0 = email.GetRelatedContentID(0);
console.log("Related item 0 Content-ID: " + cid0);

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