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Node.js | zlib.constants Property
  • Last Updated : 21 Mar, 2020

The zlib.constants property is used to yields an object listing Zlib-related constants.

Syntax:

zlib.constants

Return Value: It returns all the Zlib-related constants.

Below examples illustrate the use of zlib.constants property in Node.js:

Example 1:






// Node.js program to demonstrate     
// zlib.constants property
// Including zlib module
const zlib = require("zlib");
  
// Creating a buffer
const buffer = Buffer.from('eJzT0yMA', 'base64');
  
// Calling unzip method
zlib.unzip(
  buffer,
  
  // Using a Zlib constant
  { finishFlush: zlib.constants.Z_SYNC_FLUSH },
  
  (err, buffer) => {
  
    if (!err) {
  
      console.log(buffer.toString());
    
    else
     {
      console.log(err);
    }
  });
  
 // Calling "constants" property of zlib
 zlib.constants;


Output:

[Object: null prototype] {
  Z_NO_FLUSH: 0,
  Z_PARTIAL_FLUSH: 1,
  Z_SYNC_FLUSH: 2,
  Z_FULL_FLUSH: 3,
  Z_FINISH: 4,
  Z_BLOCK: 5,
  Z_OK: 0,
  Z_STREAM_END: 1,
  Z_NEED_DICT: 2,
  Z_ERRNO: -1,
  Z_STREAM_ERROR: -2,
  Z_DATA_ERROR: -3,
  Z_MEM_ERROR: -4,
  Z_BUF_ERROR: -5,
  Z_VERSION_ERROR: -6,
  Z_NO_COMPRESSION: 0,
  Z_BEST_SPEED: 1,
  Z_BEST_COMPRESSION: 9,
  Z_DEFAULT_COMPRESSION: -1,
  Z_FILTERED: 1,
  Z_HUFFMAN_ONLY: 2,
  Z_RLE: 3,
  Z_FIXED: 4,
  Z_DEFAULT_STRATEGY: 0,
  ZLIB_VERNUM: 4784,
  DEFLATE: 1,
  INFLATE: 2,
  GZIP: 3,
  GUNZIP: 4,
  DEFLATERAW: 5,
  INFLATERAW: 6,
  UNZIP: 7,
  BROTLI_DECODE: 8,
  BROTLI_ENCODE: 9,
  Z_MIN_WINDOWBITS: 8,
  Z_MAX_WINDOWBITS: 15,
  Z_DEFAULT_WINDOWBITS: 15,
  Z_MIN_CHUNK: 64,
  Z_MAX_CHUNK: Infinity,
  Z_DEFAULT_CHUNK: 16384,
  Z_MIN_MEMLEVEL: 1,
  Z_MAX_MEMLEVEL: 9,
  Z_DEFAULT_MEMLEVEL: 8,
  Z_MIN_LEVEL: -1,
  Z_MAX_LEVEL: 9,
  Z_DEFAULT_LEVEL: -1,
  BROTLI_OPERATION_PROCESS: 0,
  BROTLI_OPERATION_FLUSH: 1,
  BROTLI_OPERATION_FINISH: 2,
  BROTLI_OPERATION_EMIT_METADATA: 3,
  BROTLI_PARAM_MODE: 0,
  BROTLI_MODE_GENERIC: 0,
  BROTLI_MODE_TEXT: 1,
  BROTLI_MODE_FONT: 2,
  BROTLI_DEFAULT_MODE: 0,
  BROTLI_PARAM_QUALITY: 1,
  BROTLI_MIN_QUALITY: 0,
  BROTLI_MAX_QUALITY: 11,
  BROTLI_DEFAULT_QUALITY: 11,
  BROTLI_PARAM_LGWIN: 2,
  BROTLI_MIN_WINDOW_BITS: 10,
  BROTLI_MAX_WINDOW_BITS: 24,
  BROTLI_LARGE_MAX_WINDOW_BITS: 30,
  BROTLI_DEFAULT_WINDOW: 22,
  BROTLI_PARAM_LGBLOCK: 3,
  BROTLI_MIN_INPUT_BLOCK_BITS: 16,
  BROTLI_MAX_INPUT_BLOCK_BITS: 24,
  BROTLI_PARAM_DISABLE_LITERAL_CONTEXT_MODELING: 4,
  BROTLI_PARAM_SIZE_HINT: 5,
  BROTLI_PARAM_LARGE_WINDOW: 6,
  BROTLI_PARAM_NPOSTFIX: 7,
  BROTLI_PARAM_NDIRECT: 8,
  BROTLI_DECODER_RESULT_ERROR: 0,
  BROTLI_DECODER_RESULT_SUCCESS: 1,
  BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT: 2,
  BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT: 3,
  BROTLI_DECODER_PARAM_DISABLE_RING_BUFFER_REALLOCATION: 0,
  BROTLI_DECODER_PARAM_LARGE_WINDOW: 1,
  BROTLI_DECODER_NO_ERROR: 0,
  BROTLI_DECODER_SUCCESS: 1,
  BROTLI_DECODER_NEEDS_MORE_INPUT: 2,
  BROTLI_DECODER_NEEDS_MORE_OUTPUT: 3,
  BROTLI_DECODER_ERROR_FORMAT_EXUBERANT_NIBBLE: -1,
  BROTLI_DECODER_ERROR_FORMAT_RESERVED: -2,
  BROTLI_DECODER_ERROR_FORMAT_EXUBERANT_META_NIBBLE: -3,
  BROTLI_DECODER_ERROR_FORMAT_SIMPLE_HUFFMAN_ALPHABET: -4,
  BROTLI_DECODER_ERROR_FORMAT_SIMPLE_HUFFMAN_SAME: -5,
  BROTLI_DECODER_ERROR_FORMAT_CL_SPACE: -6,
  BROTLI_DECODER_ERROR_FORMAT_HUFFMAN_SPACE: -7,
  BROTLI_DECODER_ERROR_FORMAT_CONTEXT_MAP_REPEAT: -8,
  BROTLI_DECODER_ERROR_FORMAT_BLOCK_LENGTH_1: -9,
  BROTLI_DECODER_ERROR_FORMAT_BLOCK_LENGTH_2: -10,
  BROTLI_DECODER_ERROR_FORMAT_TRANSFORM: -11,
  BROTLI_DECODER_ERROR_FORMAT_DICTIONARY: -12,
  BROTLI_DECODER_ERROR_FORMAT_WINDOW_BITS: -13,
  BROTLI_DECODER_ERROR_FORMAT_PADDING_1: -14,
  BROTLI_DECODER_ERROR_FORMAT_PADDING_2: -15,
  BROTLI_DECODER_ERROR_FORMAT_DISTANCE: -16,
  BROTLI_DECODER_ERROR_DICTIONARY_NOT_SET: -19,
  BROTLI_DECODER_ERROR_INVALID_ARGUMENTS: -20,
  BROTLI_DECODER_ERROR_ALLOC_CONTEXT_MODES: -21,
  BROTLI_DECODER_ERROR_ALLOC_TREE_GROUPS: -22,
  BROTLI_DECODER_ERROR_ALLOC_CONTEXT_MAP: -25,
  BROTLI_DECODER_ERROR_ALLOC_RING_BUFFER_1: -26,
  BROTLI_DECODER_ERROR_ALLOC_RING_BUFFER_2: -27,
  BROTLI_DECODER_ERROR_ALLOC_BLOCK_TYPE_TREES: -30,
  BROTLI_DECODER_ERROR_UNREACHABLE: -31 }
..

Example 2:




// Node.js program to demonstrate     
// zlib.constants property
// Including zlib module
const zlib = require("zlib");
  
// Creating a buffer
const buffer = Buffer.from('eJzT0yMA', 'base64');
  
// Calling unzip method
zlib.unzip(
  buffer,
  
  // Using a different Zlib constant
  { finishFlush: zlib.constants.Z_NO_FLUSH },
  
  (err, buffer) => {
  
    if (!err) {
  
      console.log(buffer.toString());
    
    else
     {
      console.log(err);
    }
  });
  
 // Calling "constants" property of zlib
 zlib.constants;


Output

[Object: null prototype] {
  Z_NO_FLUSH: 0,
  Z_PARTIAL_FLUSH: 1,
  Z_SYNC_FLUSH: 2,
  Z_FULL_FLUSH: 3,
  Z_FINISH: 4,
  Z_BLOCK: 5,
  Z_OK: 0,
  Z_STREAM_END: 1,
  Z_NEED_DICT: 2,
  Z_ERRNO: -1,
  Z_STREAM_ERROR: -2,
  Z_DATA_ERROR: -3,
  Z_MEM_ERROR: -4,
  Z_BUF_ERROR: -5,
  Z_VERSION_ERROR: -6,
  Z_NO_COMPRESSION: 0,
  Z_BEST_SPEED: 1,
  Z_BEST_COMPRESSION: 9,
  Z_DEFAULT_COMPRESSION: -1,
  Z_FILTERED: 1,
  Z_HUFFMAN_ONLY: 2,
  Z_RLE: 3,
  Z_FIXED: 4,
  Z_DEFAULT_STRATEGY: 0,
  ZLIB_VERNUM: 4784,
  DEFLATE: 1,
  INFLATE: 2,
  GZIP: 3,
  GUNZIP: 4,
  DEFLATERAW: 5,
  INFLATERAW: 6,
  UNZIP: 7,
  BROTLI_DECODE: 8,
  BROTLI_ENCODE: 9,
  Z_MIN_WINDOWBITS: 8,
  Z_MAX_WINDOWBITS: 15,
  Z_DEFAULT_WINDOWBITS: 15,
  Z_MIN_CHUNK: 64,
  Z_MAX_CHUNK: Infinity,
  Z_DEFAULT_CHUNK: 16384,
  Z_MIN_MEMLEVEL: 1,
  Z_MAX_MEMLEVEL: 9,
  Z_DEFAULT_MEMLEVEL: 8,
  Z_MIN_LEVEL: -1,
  Z_MAX_LEVEL: 9,
  Z_DEFAULT_LEVEL: -1,
  BROTLI_OPERATION_PROCESS: 0,
  BROTLI_OPERATION_FLUSH: 1,
  BROTLI_OPERATION_FINISH: 2,
  BROTLI_OPERATION_EMIT_METADATA: 3,
  BROTLI_PARAM_MODE: 0,
  BROTLI_MODE_GENERIC: 0,
  BROTLI_MODE_TEXT: 1,
  BROTLI_MODE_FONT: 2,
  BROTLI_DEFAULT_MODE: 0,
  BROTLI_PARAM_QUALITY: 1,
  BROTLI_MIN_QUALITY: 0,
  BROTLI_MAX_QUALITY: 11,
  BROTLI_DEFAULT_QUALITY: 11,
  BROTLI_PARAM_LGWIN: 2,
  BROTLI_MIN_WINDOW_BITS: 10,
  BROTLI_MAX_WINDOW_BITS: 24,
  BROTLI_LARGE_MAX_WINDOW_BITS: 30,
  BROTLI_DEFAULT_WINDOW: 22,
  BROTLI_PARAM_LGBLOCK: 3,
  BROTLI_MIN_INPUT_BLOCK_BITS: 16,
  BROTLI_MAX_INPUT_BLOCK_BITS: 24,
  BROTLI_PARAM_DISABLE_LITERAL_CONTEXT_MODELING: 4,
  BROTLI_PARAM_SIZE_HINT: 5,
  BROTLI_PARAM_LARGE_WINDOW: 6,
  BROTLI_PARAM_NPOSTFIX: 7,
  BROTLI_PARAM_NDIRECT: 8,
  BROTLI_DECODER_RESULT_ERROR: 0,
  BROTLI_DECODER_RESULT_SUCCESS: 1,
  BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT: 2,
  BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT: 3,
  BROTLI_DECODER_PARAM_DISABLE_RING_BUFFER_REALLOCATION: 0,
  BROTLI_DECODER_PARAM_LARGE_WINDOW: 1,
  BROTLI_DECODER_NO_ERROR: 0,
  BROTLI_DECODER_SUCCESS: 1,
  BROTLI_DECODER_NEEDS_MORE_INPUT: 2,
  BROTLI_DECODER_NEEDS_MORE_OUTPUT: 3,
  BROTLI_DECODER_ERROR_FORMAT_EXUBERANT_NIBBLE: -1,
  BROTLI_DECODER_ERROR_FORMAT_RESERVED: -2,
  BROTLI_DECODER_ERROR_FORMAT_EXUBERANT_META_NIBBLE: -3,
  BROTLI_DECODER_ERROR_FORMAT_SIMPLE_HUFFMAN_ALPHABET: -4,
  BROTLI_DECODER_ERROR_FORMAT_SIMPLE_HUFFMAN_SAME: -5,
  BROTLI_DECODER_ERROR_FORMAT_CL_SPACE: -6,
  BROTLI_DECODER_ERROR_FORMAT_HUFFMAN_SPACE: -7,
  BROTLI_DECODER_ERROR_FORMAT_CONTEXT_MAP_REPEAT: -8,
  BROTLI_DECODER_ERROR_FORMAT_BLOCK_LENGTH_1: -9,
  BROTLI_DECODER_ERROR_FORMAT_BLOCK_LENGTH_2: -10,
  BROTLI_DECODER_ERROR_FORMAT_TRANSFORM: -11,
  BROTLI_DECODER_ERROR_FORMAT_DICTIONARY: -12,
  BROTLI_DECODER_ERROR_FORMAT_WINDOW_BITS: -13,
  BROTLI_DECODER_ERROR_FORMAT_PADDING_1: -14,
  BROTLI_DECODER_ERROR_FORMAT_PADDING_2: -15,
  BROTLI_DECODER_ERROR_FORMAT_DISTANCE: -16,
  BROTLI_DECODER_ERROR_DICTIONARY_NOT_SET: -19,
  BROTLI_DECODER_ERROR_INVALID_ARGUMENTS: -20,
  BROTLI_DECODER_ERROR_ALLOC_CONTEXT_MODES: -21,
  BROTLI_DECODER_ERROR_ALLOC_TREE_GROUPS: -22,
  BROTLI_DECODER_ERROR_ALLOC_CONTEXT_MAP: -25,
  BROTLI_DECODER_ERROR_ALLOC_RING_BUFFER_1: -26,
  BROTLI_DECODER_ERROR_ALLOC_RING_BUFFER_2: -27,
  BROTLI_DECODER_ERROR_ALLOC_BLOCK_TYPE_TREES: -30,
  BROTLI_DECODER_ERROR_UNREACHABLE: -31 }
..

Reference: https://nodejs.org/api/zlib.html#zlib_zlib_constants_1

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