(Node.js) Chilkat Zip API Concepts

This example helps clarify some common misconceptions w/ using the Chilkat Zip API.

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 zip = new chilkat.Zip();

    // To clarify some concepts, this example will create a new .zip containing 2 files.

    // The NewZip method is called to initialize the zip object to a new and empty state.
    // It does not actually create the .zip file.  It simply intializes the object.
    // if the zip object did not contain anything previously, then this method could be skipped
    // altogether.  It has the side-effect of setting the zip.FileName property.
    var success = zip.NewZip("test.zip");
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // The FileName property should now contain "test.zip".  This is the name of the .zip
    // that is written when WriteZip or WriteZipAndClose is called.
    console.log("zip filename = " + zip.FileName);

    // When a file is "appended" to the zip object, we are really just appending a reference
    // to the file in the filesystem.  A "zip entry" is added to the zip object and this entry
    // can be one of several types.  It can point to a file.  It can contain uncompressed binary
    // or text data, it can point to an entry in the already-opened zip (if we had called OpenZip 
    // instead), etc.  

    // Now.. add a reference to a single file by calling AppendOneFileOrDir
    // Note: On Windows, forward slashes are equivalent to backslashes
    var saveExtraPath = false;
    success = zip.AppendOneFileOrDir("/temp/abc123/HelloWorld123.txt",saveExtraPath);
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // We now have a zip object with one entry, which points to the file /temp/abc123/HelloWorld123.txt
    // If desired, we could change the filename of the zip entry so that when the zip is written,
    // the file has a different name:
    // entry: ZipEntry
    var entry = zip.GetEntryByIndex(0);
    entry.FileName = "helloWorld.txt";

    // When the zip is actually written, the entry's data will stream from /temp/abc123/HelloWorld123.txt
    // and be compressed into an entry within the .zip having the filename "helloWorld.txt"

    // Now add another entry, this time from a string containing the file content:
    entry = zip.AppendString2("HelloWorld2.txt","hello world!","utf-8");

    // Examine the entries in the zip so far..
    // Each entry can be one of the following types:

    // 0 -- Mapped Entry: An entry in an existing Zip file.
    // 1 -- File Entry: A file not yet in memory, but referenced. 
    //      These entries are added by calling AppendFiles, AppendFilesEx, AppendOneFileOrDir, etc.
    // 2 -- Data Entry: An entry containing uncompressed data from memory. 
    //      These entries are added by calling AppendData, AppendString, etc.
    // 3 -- Null Entry: An entry that no longer exists in the .zip.
    // 4 -- New Directory Entry: A directory entry added by calling AppendNewDir. 

    var i;
    var n = zip.NumEntries;
    for (i = 0; i <= n - 1; i++) {

        entry = zip.GetEntryByIndex(i);
        console.log(entry.FileName + ", type=" + entry.EntryType);

    }

    // Write the "test.zip" file.
    success = zip.WriteZip();
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // Our zip object still contains 2 entries, but now they point to the entries within the 
    // test.zip  (We called WriteZip, which writes the .zip but does not close it.  Instead,
    // the entries of the zip object are updated to become "mapped" entries.
    // For example:

    n = zip.NumEntries;
    for (i = 0; i <= n - 1; i++) {

        entry = zip.GetEntryByIndex(i);
        console.log(entry.FileName + ", type=" + entry.EntryType);

    }

    // Finally, close the zip
    zip.CloseZip();

}

chilkatExample();