(Node.js) Download IMAP Message Set using FetchBundle

Demonstrates how to read IMAP emails using the FetchBundle method.

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 imap = new chilkat.Imap();

    // Connect using TLS.
    imap.Ssl = true;
    imap.Port = 993;
    var success = imap.Connect("imap.example.com");
    if (success !== true) {
        console.log(imap.LastErrorText);
        return;
    }

    // Authenticate
    success = imap.Login("email_account_login","email_account_password");
    if (success !== true) {
        console.log(imap.LastErrorText);
        return;
    }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success !== true) {
        console.log(imap.LastErrorText);
        return;
    }

    // Search for messages with the word "test" in the subject.
    var fetchUids = true;
    // messageSet: MessageSet
    var messageSet = imap.Search("Subject test",fetchUids);
    if (imap.LastMethodSuccess !== true) {
        console.log(imap.LastErrorText);
        return;
    }

    // Download the messages in a single call to FetchBundle.
    // 
    // This only makes sense if the number of emails to be downloaded is not too large.  
    // For example, you wouldn't want to download 10000 emails in a single call to FetchBundle.
    // Why? For two reasons:  (1) It could potentially cause an out-of-memory condition, and 
    // (2) it would take an extremely large amount of time.  The longer the amount of time,
    // the greater the likelihood of some kind of external networking or server problem occuring,
    // and if it happens, then you would need to re-download everything from the beginning again.
    // For large numbers of emails, it's better to loop over the emails in the message set
    // and download/process one at a time as shown here: Download IMAP Messages One at a Time
    // Downloading one message at a time makes it possible to resume the downloads rather than restart the entire operation all over again.

    // If the message set is reasonable in size, you can download all at once using FetchBundle:

    console.log("Number of messages = " + messageSet.Count);

    // bundle: EmailBundle
    var bundle = imap.FetchBundle(messageSet);
    if (imap.LastMethodSuccess == false) {

        console.log(imap.LastErrorText);
        return;
    }

    // Display the Subject and From of each email.
    var i = 0;
    var numEmails = bundle.MessageCount;
    while (i < numEmails) {
        // email: Email
        var email = bundle.GetEmail(i);

        console.log(email.GetHeaderField("Date"));
        console.log(email.Subject);
        console.log(email.From);
        console.log("--");

        i = i+1;
    }


}

chilkatExample();