Compression Node.js Reference Documentation
Compression
Current Version: 11.0.0
Implements the Bzip2, Deflate, and LZW compression algorithms.
Object Creation
var obj = new chilkat.Compression();
Properties
Algorithm
· string
Specifies the compression algorithm: "deflate", "zlib", "bzip2", or "lzw". Note that "ppmd" is deprecated and should not be used. It was only available for 32-bit systems and specifically used the "J" variant. Please transition to one of the recommended algorithms.
topCharset
· string
Specifies the character encoding for compressing or decompressing strings. Options include utf-8
(default), windows-1252
, Shift_JIS
, iso-8859-2
, and others.
DebugLogFilePath
· string
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
DeflateLevel
· integer
This property allows for customization of the compression level for the "deflate" and "zlib" compression algoirthms. ("zlib" is just the deflate algorithm with a zlib header.) A value of 0 = no compression, while 9 = maximum compression. The default is 6.
topEncodingMode
· string
Controls the encoding expected by methods ending in "ENC", such as CompressBytesENC. Valid values are "base64", "hex", "url", and "quoted-printable". Compression methods ending in ENC return the binary compressed data as an encoded string using this encoding. Decompress methods expect the input string to be this encoding.
topFirstChunk
· boolean
This property applies to FirstChunk
and LastChunk
aware compression and decompression methods. It signifies that the data being compressed is the first of multiple chunks.
The default value is true
.
When both FirstChunk
and LastChunk
, it means the entire amount of data to be compressed or decompressed is presented in a single call.
LastChunk
· boolean
This property applies to FirstChunk
and LastChunk
aware compression and decompression methods. It signifies that the data being compressed is the last of multiple chunks.
The default value is true
.
When both FirstChunk
and LastChunk
, it means the entire amount of data to be compressed or decompressed is presented in a single call.
LastErrorHtml
· string, read-only
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
· string, read-only
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
· string, read-only
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
· boolean
Indicates the success or failure of the most recent method call: true
means success, false
means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.
UncommonOptions
· string
This is a catch-all property to be used for uncommon needs. This property defaults to the empty string and should typically remain empty.
Can be set to a list of the following comma separated keywords:
Crypt2CompressHdr
- Duplicates the compression and decompression as implemented in the deprecated and removed Crypt2 compression functions.
VerboseLogging
· boolean
If set to true
, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false
. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
· string, read-only
Methods
CompressBd
· Returns Boolean (true for success, false for failure).
· bd BinData
Compresses the data contained in bd. This method is not FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
CompressBdAsync (1)
· Returns a Task
· bd BinData
Creates an asynchronous task to call the CompressBd method with the arguments provided.
Returns null
on failure
CompressBd2
· Returns Boolean (true for success, false for failure).
· bdIn BinData
· bdOut BinData
This method compresses the data in bdIn without modifying it and appends the compressed data to bdOut. It is also FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
topCompressBd2Async (1)
· Returns a Task
· bdIn BinData
· bdOut BinData
Creates an asynchronous task to call the CompressBd2 method with the arguments provided.
Returns null
on failure
CompressBytes
· Returns a Buffer.
CompressBytesAsync (1)
· Returns a Task
· data Buffer
Creates an asynchronous task to call the CompressBytes method with the arguments provided.
Returns null
on failure
CompressEncryptFile
· Returns Boolean (true for success, false for failure).
· cryptParams JsonObject
· srcPath String
· destPath String
Performs file-to-file compression and encryption. Files of any size may be compressed because the file is compressed and encrypted internally in streaming mode.
Returns true for success, false for failure.
CompressEncryptFileAsync (1)
· Returns a Task
· cryptParams JsonObject
· srcPath String
· destPath String
Creates an asynchronous task to call the CompressEncryptFile method with the arguments provided.
Returns null
on failure
CompressFile
· Returns Boolean (true for success, false for failure).
· srcPath String
· destPath String
Performs file-to-file compression. Files of any size may be compressed because the file is compressed internally in streaming mode.
Returns true for success, false for failure.
CompressFileAsync (1)
· Returns a Task
· srcPath String
· destPath String
Creates an asynchronous task to call the CompressFile method with the arguments provided.
Returns null
on failure
CompressSb
· Returns Boolean (true for success, false for failure).
· sb StringBuilder
· binData BinData
Compresses the contents of sb and appends the compressed bytes to binData.
This method is FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
topCompressSbAsync (1)
· Returns a Task
· sb StringBuilder
· binData BinData
Creates an asynchronous task to call the CompressSb method with the arguments provided.
Returns null
on failure
CompressStr
· Returns Boolean (true for success, false for failure).
· str String
· bd BinData
Compresses a string and appends to bd. The byte representation (character encoding) of the actual bytes to be compressed is determined by the Charset
property. This method is FirstChunk
/ LastChunk
aware.
Returns true for success, false for failure.
topCompressStrAsync (1)
· Returns a Task
· str String
· bd BinData
Creates an asynchronous task to call the CompressStr method with the arguments provided.
Returns null
on failure
CompressStream
· Returns Boolean (true for success, false for failure).
· strm Stream
Compresses a stream. Internally, the strm's source is read, compressed, and the compressed data written to the strm's sink. It does this in streaming fashion. Extremely large or even infinite streams can be compressed with stable ungrowing memory usage.
Returns true for success, false for failure.
CompressStreamAsync (1)
· Returns a Task
· strm Stream
Creates an asynchronous task to call the CompressStream method with the arguments provided.
Returns null
on failure
CompressString
· Returns a Buffer.
CompressStringAsync (1)
· Returns a Task
· str String
Creates an asynchronous task to call the CompressString method with the arguments provided.
Returns null
on failure
CompressStringENC
· Returns a String.
· str String
Compresses a string and returns the compressed data encoded to a string. The output encoding (hex, base64, etc.) is determined by the EncodingMode property setting.
Returns null
on failure
CompressStringENCAsync (1)
· Returns a Task
· str String
Creates an asynchronous task to call the CompressStringENC method with the arguments provided.
Returns null
on failure
DecompressBd
· Returns Boolean (true for success, false for failure).
· bd BinData
Decompresses the data contained in bd. This method is not FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
DecompressBdAsync (1)
· Returns a Task
· bd BinData
Creates an asynchronous task to call the DecompressBd method with the arguments provided.
Returns null
on failure
DecompressBd2
· Returns Boolean (true for success, false for failure).
· bdIn BinData
· bdOut BinData
This method decompresses the data in bdIn without modifying it and appends the decompressed data to bdOut. It is also FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
topDecompressBd2Async (1)
· Returns a Task
· bdIn BinData
· bdOut BinData
Creates an asynchronous task to call the DecompressBd2 method with the arguments provided.
Returns null
on failure
DecompressBytes
· Returns a Buffer.
This method decompresses bytes.
This method is FirstChunk
/LastChunk
aware.
Returns null
on failure
DecompressBytesAsync (1)
· Returns a Task
· data Buffer
Creates an asynchronous task to call the DecompressBytes method with the arguments provided.
Returns null
on failure
DecompressFile
· Returns Boolean (true for success, false for failure).
· srcPath String
· destPath String
Performs file-to-file decompression (the opposite of CompressFile). Internally the file is decompressed in streaming mode which allows files of any size to be decompressed.
Returns true for success, false for failure.
DecompressFileAsync (1)
· Returns a Task
· srcPath String
· destPath String
Creates an asynchronous task to call the DecompressFile method with the arguments provided.
Returns null
on failure
DecompressSb
· Returns Boolean (true for success, false for failure).
· binData BinData
· sb StringBuilder
Decompresses the contents of binData and appends the decompressed string to sb.
This method is FirstChunk
/LastChunk
aware.
Returns true for success, false for failure.
topDecompressSbAsync (1)
· Returns a Task
· binData BinData
· sb StringBuilder
Creates an asynchronous task to call the DecompressSb method with the arguments provided.
Returns null
on failure
DecompressStream
· Returns Boolean (true for success, false for failure).
· strm Stream
Decompresses a stream. Internally, the strm's source is read, decompressed, and the decompressed data written to the strm's sink. It does this in streaming fashion. Extremely large or even infinite streams can be decompressed with stable ungrowing memory usage.
Returns true for success, false for failure.
DecompressStreamAsync (1)
· Returns a Task
· strm Stream
Creates an asynchronous task to call the DecompressStream method with the arguments provided.
Returns null
on failure
DecryptDecompressFile
· Returns Boolean (true for success, false for failure).
· cryptParams JsonObject
· srcPath String
· destPath String
Performs file-to-file decryption and decompression.
Returns true for success, false for failure.
DecryptDecompressFileAsync (1)
· Returns a Task
· cryptParams JsonObject
· srcPath String
· destPath String
Creates an asynchronous task to call the DecryptDecompressFile method with the arguments provided.
Returns null
on failure
LoadTaskCaller
· Returns Boolean (true for success, false for failure).
· task Task
Deprecated
BeginCompressBytes
· Returns a Buffer.
Large amounts of binary byte data may be compressed in chunks by first calling BeginCompressBytes, followed by 0 or more calls to MoreCompressedBytes, and ending with a final call to EndCompressBytes. Each call returns 0 or more bytes of compressed data which may be output to a compressed data stream (such as a file, socket, etc.).
Returns null
on failure
BeginCompressBytesENC
· Returns a String.
· data Buffer
Large amounts of binary byte data may be compressed in chunks by first calling BeginCompressBytesENC, followed by 0 or more calls to MoreCompressedBytesENC, and ending with a final call to EndCompressBytesENC. Each call returns 0 or more characters of compressed data (encoded as a string according to the EncodingMode property setting) which may be output to a compressed data stream (such as a file, socket, etc.).
Returns null
on failure
BeginCompressString
· Returns a Buffer.
Large amounts of string data may be compressed in chunks by first calling BeginCompressString, followed by 0 or more calls to MoreCompressedString, and ending with a final call to EndCompressString. Each call returns 0 or more bytes of compressed data which may be output to a compressed data stream (such as a file, socket, etc.).
Returns null
on failure
BeginCompressStringENC
· Returns a String.
· str String
Large amounts of string data may be compressed in chunks by first calling BeginCompressStringENC, followed by 0 or more calls to MoreCompressedStringENC, and ending with a final call to EndCompressStringENC. Each call returns 0 or more characters of compressed data (encoded as a string according to the EncodingMode property setting) which may be output to a compressed data stream (such as a file, socket, etc.).
Returns null
on failure
BeginDecompressBytes
· Returns a Buffer.
A compressed data stream may be decompressed in chunks by first calling BeginDecompressBytes, followed by 0 or more calls to MoreDecompressedBytes, and ending with a final call to EndDecompressBytes. Each call returns 0 or more bytes of decompressed data.
Returns null
on failure
BeginDecompressBytesENC
· Returns a Buffer.
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
A compressed data stream may be decompressed in chunks by first calling BeginDecompressBytesENC, followed by 0 or more calls to MoreDecompressedBytesENC, and ending with a final call to EndDecompressBytesENC. Each call returns 0 or more bytes of decompressed data.
Returns null
on failure
BeginDecompressString
· Returns a String.
· data Buffer
A compressed data stream may be decompressed in chunks by first calling BeginDecompressString, followed by 0 or more calls to MoreDecompressedString, and ending with a final call to EndDecompressString. Each call returns 0 or more characters of decompressed text.
Returns null
on failure
BeginDecompressStringENC
· Returns a String.
· str String
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
A compressed data stream may be decompressed in chunks by first calling BeginDecompressStringENC, followed by 0 or more calls to MoreDecompressedStringENC, and ending with a final call to EndDecompressStringENC. Each call returns 0 or more characters of decompressed text.
Returns null
on failure
EndCompressBytes
· Returns a Buffer.
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressBytes)
Returns null
on failure
EndCompressBytesENC
· Returns a String.
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressBytesENC)
Returns null
on failure
EndCompressString
· Returns a Buffer.
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressString)
Returns null
on failure
EndCompressStringENC
· Returns a String.
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressStringENC)
Returns null
on failure
EndDecompressBytes
· Returns a Buffer.
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
(See BeginDecompressBytes)
Returns null
on failure
EndDecompressBytesENC
· Returns a Buffer.
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
(See BeginDecompressBytesENC)
Returns null
on failure
EndDecompressString
· Returns a String.
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
(See BeginDecompressString)
Returns null
on failure
EndDecompressStringENC
· Returns a String.
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
(See BeginDecompressStringENC)
Returns null
on failure
MoreCompressBytes
· Returns a Buffer.
MoreCompressBytesENC
· Returns a String.
· data Buffer
MoreCompressString
· Returns a Buffer.
MoreCompressStringENC
· Returns a String.
· str String
MoreDecompressBytes
· Returns a Buffer.
MoreDecompressBytesENC
· Returns a Buffer.
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
(See BeginDecompressBytesENC)
Returns null
on failure
MoreDecompressString
· Returns a String.
· data Buffer
MoreDecompressStringENC
· Returns a String.
· str String
The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.
(See BeginDecompressStringENC)
Returns null
on failure