{ "type": "module", "source": "doc/api/zlib_iter.md", "modules": [ { "textRaw": "Iterable Compression", "name": "iterable_compression", "introduced_in": "v25.9.0", "type": "module", "stability": 1, "stabilityText": "Experimental", "desc": "

The node:zlib/iter module provides compression and decompression transforms\nfor use with the node:stream/iter iterable streams API.

\n

This module is available only when the --experimental-stream-iter CLI flag\nis enabled.

\n

Each algorithm has both an async variant (stateful async generator, for use\nwith pull() and pipeTo()) and a sync variant (stateful sync\ngenerator, for use with pullSync() and pipeToSync()).

\n

The async transforms run compression on the libuv threadpool, overlapping\nI/O with JavaScript execution. The sync transforms run compression directly\non the main thread.

\n
\n

Note: The defaults for these transforms are tuned for streaming throughput,\nand differ from the defaults in node:zlib. In particular, gzip/deflate\ndefault to level 4 (not 6) and memLevel 9 (not 8), and Brotli defaults to\nquality 6 (not 11). These choices match common HTTP server configurations\nand provide significantly faster compression with only a small reduction in\ncompression ratio. All defaults can be overridden via options.

\n
\n
import { from, pull, bytes, text } from 'node:stream/iter';\nimport { compressGzip, decompressGzip } from 'node:zlib/iter';\n\n// Async round-trip\nconst compressed = await bytes(pull(from('hello'), compressGzip()));\nconst original = await text(pull(from(compressed), decompressGzip()));\nconsole.log(original); // 'hello'\n
\n
const { from, pull, bytes, text } = require('node:stream/iter');\nconst { compressGzip, decompressGzip } = require('node:zlib/iter');\n\nasync function run() {\n  const compressed = await bytes(pull(from('hello'), compressGzip()));\n  const original = await text(pull(from(compressed), decompressGzip()));\n  console.log(original); // 'hello'\n}\n\nrun().catch(console.error);\n
\n
import { fromSync, pullSync, textSync } from 'node:stream/iter';\nimport { compressGzipSync, decompressGzipSync } from 'node:zlib/iter';\n\n// Sync round-trip\nconst compressed = pullSync(fromSync('hello'), compressGzipSync());\nconst original = textSync(pullSync(compressed, decompressGzipSync()));\nconsole.log(original); // 'hello'\n
\n
const { fromSync, pullSync, textSync } = require('node:stream/iter');\nconst { compressGzipSync, decompressGzipSync } = require('node:zlib/iter');\n\nconst compressed = pullSync(fromSync('hello'), compressGzipSync());\nconst original = textSync(pullSync(compressed, decompressGzipSync()));\nconsole.log(original); // 'hello'\n
", "methods": [ { "textRaw": "`compressBrotli([options])`", "name": "compressBrotli", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`compressBrotliSync([options])`", "name": "compressBrotliSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`params` {Object} Key-value object where keys and values are `zlib.constants` entries. The most important compressor parameters are:", "name": "params", "type": "Object", "desc": "Key-value object where keys and values are `zlib.constants` entries. The most important compressor parameters are:", "options": [ { "textRaw": "`BROTLI_PARAM_MODE` -- `BROTLI_MODE_GENERIC` (default), `BROTLI_MODE_TEXT`, or `BROTLI_MODE_FONT`.", "name": "BROTLI_PARAM_MODE", "desc": "- `BROTLI_MODE_GENERIC` (default), `BROTLI_MODE_TEXT`, or `BROTLI_MODE_FONT`." }, { "textRaw": "`BROTLI_PARAM_QUALITY` -- ranges from `BROTLI_MIN_QUALITY` to `BROTLI_MAX_QUALITY`. **Default:** `6` (not `BROTLI_DEFAULT_QUALITY` which is 11). Quality 6 is appropriate for streaming; quality 11 is intended for offline/build-time compression.", "name": "BROTLI_PARAM_QUALITY", "default": "`6` (not `BROTLI_DEFAULT_QUALITY` which is 11). Quality 6 is appropriate for streaming; quality 11 is intended for offline/build-time compression", "desc": "- ranges from `BROTLI_MIN_QUALITY` to `BROTLI_MAX_QUALITY`." }, { "textRaw": "`BROTLI_PARAM_SIZE_HINT` -- expected input size. **Default:** `0` (unknown).", "name": "BROTLI_PARAM_SIZE_HINT", "default": "`0` (unknown)", "desc": "- expected input size." }, { "textRaw": "`BROTLI_PARAM_LGWIN` -- window size (log2). **Default:** `20` (1 MB). The Brotli library default is 22 (4 MB); the reduced default saves memory without significant compression impact for streaming workloads.", "name": "BROTLI_PARAM_LGWIN", "default": "`20` (1 MB). The Brotli library default is 22 (4 MB); the reduced default saves memory without significant compression impact for streaming workloads", "desc": "- window size (log2)." }, { "textRaw": "`BROTLI_PARAM_LGBLOCK` -- input block size (log2). See the Brotli compressor options in the zlib documentation for the full list.", "name": "BROTLI_PARAM_LGBLOCK", "desc": "- input block size (log2). See the Brotli compressor options in the zlib documentation for the full list." } ] }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a Brotli compression transform. Output is compatible with\nzlib.brotliDecompress() and decompressBrotli()/decompressBrotliSync().

" }, { "textRaw": "`compressDeflate([options])`", "name": "compressDeflate", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`compressDeflateSync([options])`", "name": "compressDeflateSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`level` {number} Compression level (`0`-`9`). **Default:** `4`.", "name": "level", "type": "number", "default": "`4`", "desc": "Compression level (`0`-`9`)." }, { "textRaw": "`windowBits` {number} **Default:** `Z_DEFAULT_WINDOWBITS` (15).", "name": "windowBits", "type": "number", "default": "`Z_DEFAULT_WINDOWBITS` (15)" }, { "textRaw": "`memLevel` {number} **Default:** `9`.", "name": "memLevel", "type": "number", "default": "`9`" }, { "textRaw": "`strategy` {number} **Default:** `Z_DEFAULT_STRATEGY`.", "name": "strategy", "type": "number", "default": "`Z_DEFAULT_STRATEGY`" }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a deflate compression transform. Output is compatible with\nzlib.inflate() and decompressDeflate()/decompressDeflateSync().

" }, { "textRaw": "`compressGzip([options])`", "name": "compressGzip", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`compressGzipSync([options])`", "name": "compressGzipSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`level` {number} Compression level (`0`-`9`). **Default:** `4`.", "name": "level", "type": "number", "default": "`4`", "desc": "Compression level (`0`-`9`)." }, { "textRaw": "`windowBits` {number} **Default:** `Z_DEFAULT_WINDOWBITS` (15).", "name": "windowBits", "type": "number", "default": "`Z_DEFAULT_WINDOWBITS` (15)" }, { "textRaw": "`memLevel` {number} **Default:** `9`.", "name": "memLevel", "type": "number", "default": "`9`" }, { "textRaw": "`strategy` {number} **Default:** `Z_DEFAULT_STRATEGY`.", "name": "strategy", "type": "number", "default": "`Z_DEFAULT_STRATEGY`" }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a gzip compression transform. Output is compatible with zlib.gunzip()\nand decompressGzip()/decompressGzipSync().

" }, { "textRaw": "`compressZstd([options])`", "name": "compressZstd", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`compressZstdSync([options])`", "name": "compressZstdSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`params` {Object} Key-value object where keys and values are `zlib.constants` entries. The most important compressor parameters are:", "name": "params", "type": "Object", "desc": "Key-value object where keys and values are `zlib.constants` entries. The most important compressor parameters are:", "options": [ { "textRaw": "`ZSTD_c_compressionLevel` -- **Default:** `ZSTD_CLEVEL_DEFAULT` (3).", "name": "ZSTD_c_compressionLevel", "default": "`ZSTD_CLEVEL_DEFAULT` (3)", "desc": "-" }, { "textRaw": "`ZSTD_c_checksumFlag` -- generate a checksum. **Default:** `0`.", "name": "ZSTD_c_checksumFlag", "default": "`0`", "desc": "- generate a checksum." }, { "textRaw": "`ZSTD_c_strategy` -- compression strategy. Values include `ZSTD_fast`, `ZSTD_dfast`, `ZSTD_greedy`, `ZSTD_lazy`, `ZSTD_lazy2`, `ZSTD_btlazy2`, `ZSTD_btopt`, `ZSTD_btultra`, `ZSTD_btultra2`. See the Zstd compressor options in the zlib documentation for the full list.", "name": "ZSTD_c_strategy", "desc": "- compression strategy. Values include `ZSTD_fast`, `ZSTD_dfast`, `ZSTD_greedy`, `ZSTD_lazy`, `ZSTD_lazy2`, `ZSTD_btlazy2`, `ZSTD_btopt`, `ZSTD_btultra`, `ZSTD_btultra2`. See the Zstd compressor options in the zlib documentation for the full list." } ] }, { "textRaw": "`pledgedSrcSize` {number} Expected uncompressed size (optional hint).", "name": "pledgedSrcSize", "type": "number", "desc": "Expected uncompressed size (optional hint)." }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a Zstandard compression transform. Output is compatible with\nzlib.zstdDecompress() and decompressZstd()/decompressZstdSync().

" }, { "textRaw": "`decompressBrotli([options])`", "name": "decompressBrotli", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`decompressBrotliSync([options])`", "name": "decompressBrotliSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`params` {Object} Key-value object where keys and values are `zlib.constants` entries. Available decompressor parameters:", "name": "params", "type": "Object", "desc": "Key-value object where keys and values are `zlib.constants` entries. Available decompressor parameters:", "options": [ { "textRaw": "`BROTLI_DECODER_PARAM_DISABLE_RING_BUFFER_REALLOCATION` -- boolean flag affecting internal memory allocation.", "name": "BROTLI_DECODER_PARAM_DISABLE_RING_BUFFER_REALLOCATION", "desc": "- boolean flag affecting internal memory allocation." }, { "textRaw": "`BROTLI_DECODER_PARAM_LARGE_WINDOW` -- boolean flag enabling \"Large Window Brotli\" mode (not compatible with RFC 7932). See the Brotli decompressor options in the zlib documentation for details.", "name": "BROTLI_DECODER_PARAM_LARGE_WINDOW", "desc": "- boolean flag enabling \"Large Window Brotli\" mode (not compatible with RFC 7932). See the Brotli decompressor options in the zlib documentation for details." } ] }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a Brotli decompression transform.

" }, { "textRaw": "`decompressDeflate([options])`", "name": "decompressDeflate", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`decompressDeflateSync([options])`", "name": "decompressDeflateSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`windowBits` {number} **Default:** `Z_DEFAULT_WINDOWBITS` (15).", "name": "windowBits", "type": "number", "default": "`Z_DEFAULT_WINDOWBITS` (15)" }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a deflate decompression transform.

" }, { "textRaw": "`decompressGzip([options])`", "name": "decompressGzip", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`decompressGzipSync([options])`", "name": "decompressGzipSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`windowBits` {number} **Default:** `Z_DEFAULT_WINDOWBITS` (15).", "name": "windowBits", "type": "number", "default": "`Z_DEFAULT_WINDOWBITS` (15)" }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a gzip decompression transform.

" }, { "textRaw": "`decompressZstd([options])`", "name": "decompressZstd", "type": "method", "signatures": [ { "params": [ { "name": "options", "optional": true } ] } ] }, { "textRaw": "`decompressZstdSync([options])`", "name": "decompressZstdSync", "type": "method", "meta": { "added": [ "v25.9.0" ], "changes": [] }, "signatures": [ { "params": [ { "textRaw": "`options` {Object}", "name": "options", "type": "Object", "options": [ { "textRaw": "`chunkSize` {number} Output buffer size. **Default:** `65536` (64 KB).", "name": "chunkSize", "type": "number", "default": "`65536` (64 KB)", "desc": "Output buffer size." }, { "textRaw": "`params` {Object} Key-value object where keys and values are `zlib.constants` entries. Available decompressor parameters:", "name": "params", "type": "Object", "desc": "Key-value object where keys and values are `zlib.constants` entries. Available decompressor parameters:", "options": [ { "textRaw": "`ZSTD_d_windowLogMax` -- maximum window size (log2) the decompressor will allocate. Limits memory usage against malicious input. See the Zstd decompressor options in the zlib documentation for details.", "name": "ZSTD_d_windowLogMax", "desc": "- maximum window size (log2) the decompressor will allocate. Limits memory usage against malicious input. See the Zstd decompressor options in the zlib documentation for details." } ] }, { "textRaw": "`dictionary` {Buffer|TypedArray|DataView}", "name": "dictionary", "type": "Buffer|TypedArray|DataView" } ], "optional": true } ], "return": { "textRaw": "Returns: {Object} A stateful transform.", "name": "return", "type": "Object", "desc": "A stateful transform." } } ], "desc": "

Create a Zstandard decompression transform.

" } ], "displayName": "Iterable Compression" } ] }