(Node.js) Unzip Binary File to Stream

Demonstrates how to unzip a large binary file to a stream to allow the application to process the uncompressed bytes chunk by chunk.

Note: This example requires Chilkat v9.5.0.67 or greater.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

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

    var zip = new chilkat.Zip();

    // First open a .zip.
    var success = zip.OpenZip("qa_data/zips/big.zip");
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // Get the entry to be unzipped to a stream..
    // entry: ZipEntry
    var entry = zip.GetEntryByIndex(0);
    if (zip.LastMethodSuccess !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    var dataStream = new chilkat.Stream();

    // unzipTask: Task
    var unzipTask = entry.UnzipToStreamAsync(dataStream);
    if (entry.LastMethodSuccess !== true) {
        console.log(entry.LastErrorText);

        return;
    }

    // Start the background unzip thread.
    unzipTask.Run();

    // We'll read the uncompressed data chunk-by-chunk and write to an output file.
    var fac = new chilkat.FileAccess();
    success = fac.OpenForWrite("qa_output/out.dat");
    if (success !== true) {
        console.log(fac.LastErrorText);

        return;
    }

    // Read the stream.  (this is reading the unzipped file data)
    var bd = new chilkat.BinData();
    while (dataStream.EndOfStream !== true) {
        // Get the next chunk of decompressed bytes.
        dataStream.ReadBd(bd);
        // Do something with it..
        // In this simple example, we'll just write to the file.
        fac.FileWriteBd(bd,0,0);
        // Clear for the next read.
        bd.Clear();
    }

    fac.FileClose();

    console.log("Success.");

}

chilkatExample();