(Node.js) Compress Large Binary File in Blocks

Compresses a large binary file in blocks. This example uses BeginCompressBytes, MoreCompressBytes, and EndCompressBytes.

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 assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var facSrc = new chilkat.FileAccess();
    var facDest = new chilkat.FileAccess();

    // Open a large binary file for reading.
    var success = facSrc.OpenForRead("qa_data/bmp/big.bmp");
    if (success !== true) {
        console.log(facSrc.LastErrorText);
        return;
    }

    // If we compress in 64K chunks, find out how many blocks there will be.
    var blockSize = 65536;
    var numBlocks = facSrc.GetNumBlocks(blockSize);

    // Open an output file for the compressed data.
    success = facDest.OpenForWrite("qa_data/bmp/compressedBmp.dat");
    if (success !== true) {
        console.log(facDest.LastErrorText);
        return;
    }

    var compress = new chilkat.Compression();
    compress.Algorithm = "deflate";

    var i = 0;
    while (i < numBlocks) {
        fileBytes = facSrc.ReadBlock(i,blockSize);
        if (i == 0) {
            compressedBytes = compress.BeginCompressBytes(fileBytes);
        }
        else {
            compressedBytes = compress.MoreCompressBytes(fileBytes);
        }

        facDest.FileWrite(compressedBytes);

        i = i+1;
    }

    // At the very end, flush any remaining compressed bytes, if any.
    compressedBytes = compress.EndCompressBytes();
    facDest.FileWrite(compressedBytes);

    facSrc.FileClose();
    facDest.FileClose();

    console.log("Finished compressing file.");

}

chilkatExample();