(Node.js) Restart/Resume FTP Download

Resume downloading a file from an FTP server.

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 ftp = new chilkat.Ftp2();

    ftp.Hostname = "ftp.example.com";
    ftp.Username = "login";
    ftp.Password = "password";

    // Connect and login to the FTP server.
    var success = ftp.Connect();
    if (success !== true) {
        console.log(ftp.LastErrorText);
        return;
    }

    // Change to the remote directory where the file is located.
    // This step is only necessary if the file is not in the root directory
    // for the FTP account.
    success = ftp.ChangeRemoteDir("temp");
    if (success !== true) {
        console.log(ftp.LastErrorText);
        return;
    }

    // To resume a download, it is assumed that the partial file
    // is already present on the local filesystem.
    // You only need to set the RestartNext property to resume
    // the download.  The Chilkat FTP component sets the resume
    // point by getting the existing size of the target (local) file.
    ftp.RestartNext = true;

    var localFilename = "big.zip";
    var remoteFilename = "big.zip";

    // Resume downloading...
    success = ftp.GetFile(remoteFilename,localFilename);
    if (success !== true) {
        console.log(ftp.LastErrorText);
        return;
    }

    success = ftp.Disconnect();

    console.log("File Downloaded!");

}

chilkatExample();