(JavaScript) Chilkat Zip API Concepts

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

Note: This example requires Chilkat v11.0.0 or greater.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

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

var zip = new CkZip();

// 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.
success = zip.NewZip("test.zip");
if (success == false) {
    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 AddFile
// Note: On Windows, forward slashes are equivalent to backslashes
var saveExtraPath = false;
success = zip.AddFile("/temp/abc123/HelloWorld123.txt",saveExtraPath);
if (success == false) {
    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:
var entry = new CkZipEntry();
zip.EntryAt(0,entry);
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:
zip.AddString("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, AddFile, 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 AddEmpty. 

var i;
var n = zip.NumEntries;
for (i = 0; i <= n - 1; i++) {
    zip.EntryAt(i,entry);
    console.log(entry.FileName + ", type=" + entry.EntryType);
}

// Write the "test.zip" file.
success = zip.WriteZip();
if (success == false) {
    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++) {
    zip.EntryAt(i,entry);
    console.log(entry.FileName + ", type=" + entry.EntryType);
}

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