---
product: Chilkat
product_version: 11.7.0
language: js
language_label: JavaScript
class: Bz2
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/jsBz2Ref.html
---
# Chilkat Bz2 — JavaScript — v11.7.0

> Chilkat 11.7.0 · language=js · class=Bz2
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/Bz2.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/js/guide.md`.

## Purpose

`Chilkat.Bz2` provides BZip2 compression and decompression for files, memory buffers, and BinData. It can create standard .bz2 file images, decompress .bz2 content back to its original bytes, and support abortable long-running operations.

For an extended overview, see [Bz2 Class Overview](https://www.chilkatsoft.com/bz2_class_overview.asp)

## Object creation, unlocking and error handling

**Object Creation**

Note: This is intended for running within a [Chilkat.Js embedded JavaScript engine](https://www.chilkatsoft.com/chilkat_javascript_engine.asp).

```
var obj = new CkBz2();
```

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in JavaScript.

How failure is reported depends on the method's return type and is stated in the note under each method below. In every case the diagnostic text is in the `LastErrorText` property of the object whose method was called.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `DebugLogFilePath` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `LastErrorHtml` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `LastErrorText` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `LastErrorXml` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `LastMethodSuccess` | read/write | Indicates the success or failure of the most recent method call: `true` means success, `false` means failure. |
| `VerboseLogging` | `VerboseLogging` | read/write | If set to `true`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `Version` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `AbortCurrent` | property, read/write | `AbortCurrent` |
| `CompressBd` | method | `var success = CompressBd(bd);` |
| `CompressFile` | method | `var success = CompressFile(inFilename, toPath);` |
| `UncompressBd` | method | `var success = UncompressBd(bd);` |
| `UncompressFile` | method | `var success = UncompressFile(inFilename, toPath);` |

## Properties

### Bz2.AbortCurrent

`Chilkat 11.7.0 · js · Bz2 · AbortCurrent · property · read/write · since 9.5.0.58`

```javascript
AbortCurrent
```

· `boolean`

Set this property to `true` to request cancellation of the compression or decompression operation currently executing on this object. Long-running operations check the request periodically; an operation that finishes quickly may complete before the request is observed.

A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to `false`. If no operation is running, a previously set value is cleared when the next method begins.

**Cancellation is cooperative:** Setting this property requests an abort; it does not guarantee immediate termination. Check the method's return value and `LastErrorText` to determine the final outcome.

## Methods

### Bz2.CompressBd

`Chilkat 11.7.0 · js · Bz2 · CompressBd · method · since 11.0.0`

```javascript
var success = CompressBd(bd);
```

· return: `boolean`; `true` for success, `false` for failure  
· bd: `CkBinData`

Compresses the current contents of `bd` in place. On success, the `BinData` no longer contains the original bytes; it contains the complete standard BZip2 stream that may be saved with a `.bz2` extension.

**In-place transformation:** Preserve a copy of the original data if it is still needed after this call. A BZip2 stream contains a stream header, one or more compressed blocks with integrity checks, and an end-of-stream marker. It does not contain archive filenames or directory entries.

Returns true for success, false for failure.

### Bz2.CompressFile

`Chilkat 11.7.0 · js · Bz2 · CompressFile · method`

```javascript
var success = CompressFile(inFilename, toPath);
```

· return: `boolean`; `true` for success, `false` for failure  
· inFilename: `string`  
· toPath: `string`

Reads the file at `inFilename` and writes its compressed bytes as a standard BZip2 stream to the file at `toPath`. The output is conventionally given a `.bz2` extension.

Both arguments must identify files, not directories. They may be absolute or relative paths, for example `data/report.txt` and `data/report.txt.bz2`.

**BZip2 is a compressor, not an archive format:** A `.bz2` file represents one compressed byte stream. It does not store the original filename, directory path, timestamps, permissions, or multiple archive entries. Formats such as `.tar.bz2` first combine files in a TAR archive and then compress that TAR stream with BZip2.

Returns true for success, false for failure.

### Bz2.UncompressBd

`Chilkat 11.7.0 · js · Bz2 · UncompressBd · method · since 11.0.0`

```javascript
var success = UncompressBd(bd);
```

· return: `boolean`; `true` for success, `false` for failure  
· bd: `CkBinData`

Decompresses the BZip2 stream currently contained in `bd` in place. On success, the `BinData` is replaced with the original uncompressed bytes.

**Input requirement:** `bd` must contain a complete, valid BZip2 stream, such as the bytes of a `.bz2` file or the output of `CompressBd`. This method operates on binary data and does not perform character-set conversion.

Returns true for success, false for failure.

### Bz2.UncompressFile

`Chilkat 11.7.0 · js · Bz2 · UncompressFile · method`

```javascript
var success = UncompressFile(inFilename, toPath);
```

· return: `boolean`; `true` for success, `false` for failure  
· inFilename: `string`  
· toPath: `string`

Reads the BZip2 stream from the file at `inFilename`, decompresses it, and writes the original uncompressed bytes to the file at `toPath`.

Both arguments must identify files, not directories. Chilkat does not derive the destination name from the `.bz2` filename because the BZip2 stream does not contain the original filename.

**Terminology:** This method decompresses BZip2 data; it does not “unzip” a ZIP archive. A `.bz2` file normally contains a single compressed byte stream rather than a collection of named files.

Returns true for success, false for failure.

## Events and callbacks

This binding has no event callbacks.

## Related classes

[`BinData`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/js/classes/BinData.md)