(Node.js) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks. This example uses BeginDecompressBytes, MoreDecompressBytes, and EndDecompressBytes.

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

    // Open a previously compressed file for decompressing.
    // See Compress Large File in Blocks

    var success = facSrc.OpenForRead("qa_data/bmp/compressedBmp.dat");
    if (success !== true) {
        console.log(facSrc.LastErrorText);
        return;
    }

    // If we compress in 32K chunks, find out how many blocks there will be.
    var blockSize = 32768;
    var numBlocks = facSrc.GetNumBlocks(blockSize);

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

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

    var i = 0;
    while (i < numBlocks) {
        compressedBytes = facSrc.ReadBlock(i,blockSize);
        if (i == 0) {
            decompressedBytes = compress.BeginDecompressBytes(compressedBytes);
        }
        else {
            decompressedBytes = compress.MoreDecompressBytes(compressedBytes);
        }

        facDest.FileWrite(decompressedBytes);

        i = i+1;
    }

    // At the very end, flush any remaining decompressed bytes, if any.
    decompressedBytes = compress.EndDecompressBytes();
    facDest.FileWrite(decompressedBytes);

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

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

}

chilkatExample();