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jsz module

This module manage zlib data compression and decompression. more.

• jsz module
• jsz::Z class
• constructor
• call operator
• Properties
• idle
• adler32
• lengthIn
• lengthOut
• Static Properties
• Constants
• example
• jsz::ZError class

jsz::Z class

constructor

• Constructor( method [, compressionLevel ] )

Constructs a new inflater or deflater object.

The method can be Z.DEFLATE to compress data or Z.INFLATE to decompress data. The compression level is like this: 0 <= compressionLevel <= 9.

note:

For Z.INFLATE method, compressionLevel argument is useless ( no sense )

example:

  var compress = new Z( Z.DEFLATE, 9 );

call operator

_string call operator( [ inputData [, forceFinish = false ] ] )

This function process inputData as a stream. If forceFinish is true, the inputData and any buffered data are flushed to the outputData. If this function is call without any argument, All remaining data are flushed. Once finished, the object can be reused to process a new stream of data.

example:

  var compress = new Z( Z.DEFLATE );
  var compressedData = compress( 'Hello ');
  compressedData += compress( 'world' );
  compressedData += compress(); // flush

example:

  var compress = new Z( Z.DEFLATE );
  var compressedData = compress( 'Hello ');
  compressedData += compress( 'world', true ); // flush

example:

  var compressedData = new Z( Z.DEFLATE )( 'Hello world', true ); // flush

Properties

idle

_boolean idle

Is true if the redy to process new data.

adler32

• dler32

Contains the adler32 checksum of the data. more.

lengthIn

• engthIn

Contains the current total amount of input data.

lengthOut

• engthOut

Contains the current total amount of output data.

Static Properties

Constants

• Z.DEFLATE

Compression method.

• Z.INFLATE

Decompression method.

example

var deflate = new Z( Z.DEFLATE, 9 );
var clearData;
var compressedData;

for ( var i = 10; i >= 0; --i ) {

   var chunk = randomString(10000);
   compressedData += deflate( chunk );
   clearData += chunk;
}
compressedData += deflate(); // flush


var inflate = new Z( Z.INFLATE );
var clearData2 = inflate( compressedData, true );

Print( 'ratio:' + compressedData.length + ': ' + Math.round( 100 * compressedData.length / clearData.length ) + '%','\n');
if ( clearData2 != clearData )

   Print('error!!!','\n');
}

code snippet

jsz::ZError class

You cannot construct this class.

Its aim is to throw as an exception on any zlib runtime error.

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