• Version 1.7.5
  • Published
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  • 1 dependency
  • MIT license


npm i @types/compression
yarn add @types/compression
pnpm add @types/compression


TypeScript definitions for compression



function compression

compression: typeof compression;
  • Returns the compression middleware using the given options. The middleware will attempt to compress response bodies for all request that traverse through the middleware, based on the given options.

    This middleware will never compress responses that include a Cache-Control header with the no-transform directive, as compressing will transform the body.

    See Also

function filter

filter: (req: express.Request, res: express.Response) => boolean;
  • The default filter function. This is used to construct a custom filter function that is an extension of the default function.

    var compression = require('compression')
    var express = require('express')
    var app = express()
    app.use(compression({ filter: shouldCompress }))
    function shouldCompress (req, res) {
    if (req.headers['x-no-compression']) {
    // don't compress responses with this request header
    return false
    // fallback to standard filter function
    return compression.filter(req, res)

    See Also


interface CompressionFilter

interface CompressionFilter {}
  • A function to decide if the response should be considered for compression.

call signature

(req: express.Request, res: express.Response): boolean;

    interface CompressionOptions

    interface CompressionOptions {}
    • compression() accepts these properties in the options object. In addition to those listed below, zlib options may be passed in to the options object.

    property chunkSize

    chunkSize?: number | undefined;

    property filter

    filter?: CompressionFilter | undefined;
    • A function to decide if the response should be considered for compression. This function is called as filter(req, res) and is expected to return true to consider the response for compression, or false to not compress the response.

      The default filter function uses the compressible module to determine if res.getHeader('Content-Type') is compressible.

      See Also

    property level

    level?: number | undefined;
    • The level of zlib compression to apply to responses. A higher level will result in better compression, but will take longer to complete. A lower level will result in less compression, but will be much faster.

      This is an integer in the range of 0 (no compression) to 9 (maximum compression). The special value -1 can be used to mean the "default compression level", which is a default compromise between speed and compression (currently equivalent to level 6).

      - -1 Default compression level (also zlib.constants.Z_DEFAULT_COMPRESSION). - 0 No compression (also zlib.constants.Z_NO_COMPRESSION). - 1 Fastest compression (also zlib.constants.Z_BEST_SPEED). - 2 - 3 - 4 - 5 - 6 (currently what zlib.constants.Z_DEFAULT_COMPRESSION points to). - 7 - 8 - 9 Best compression (also zlib.constants.Z_BEST_COMPRESSION).

      **Note** in the list above, zlib is from zlib = require('zlib').

      zlib.constants.DEFAULT_COMPRESSION or -1

      See Also

    property memLevel

    memLevel?: number | undefined;
    • This specifies how much memory should be allocated for the internal compression state and is an integer in the range of 1 (minimum level) and 9 (maximum level).

      zlib.constants.DEFAULT_MEMLEVEL or 8

      See Also

    property strategy

    strategy?: number | undefined;
    • This is used to tune the compression algorithm. This value only affects the compression ratio, not the correctness of the compressed output, even if it is not set appropriately.

      - zlib.constants.Z_DEFAULT_STRATEGY Use for normal data. - zlib.constants.Z_FILTERED Use for data produced by a filter (or predictor). Filtered data consists mostly of small values with a somewhat random distribution. In this case, the compression algorithm is tuned to compress them better. The effect is to force more Huffman coding and less string matching; it is somewhat intermediate between zlib.constants.Z_DEFAULT_STRATEGY and zlib.constants.Z_HUFFMAN_ONLY. - zlib.constants.Z_FIXED Use to prevent the use of dynamic Huffman codes, allowing for a simpler decoder for special applications. - zlib.constants.Z_HUFFMAN_ONLY Use to force Huffman encoding only (no string match). - zlib.constants.Z_RLE Use to limit match distances to one (run-length encoding). This is designed to be almost as fast as zlib.constants.Z_HUFFMAN_ONLY, but give better compression for PNG image data.

      **Note** in the list above, zlib is from zlib = require('zlib').

    property threshold

    threshold?: number | string | undefined;
    • The byte threshold for the response body size before compression is considered for the response, defaults to 1kb. This is a number of bytes or any string accepted by the bytes module.

      **Note** this is only an advisory setting; if the response size cannot be determined at the time the response headers are written, then it is assumed the response is *over* the threshold. To guarantee the response size can be determined, be sure set a Content-Length response header.

      See Also

    property windowBits

    windowBits?: number | undefined;

    index signature

    [property: string]: any;
    • In addition , zlib options may be passed in to the options object.


    namespace global

    namespace global {}

      namespace global.Express

      namespace global.Express {}

        interface Response

        interface Response {}

          method flush

          flush: () => void;
          • Forces the partially-compressed response to be flushed to the client.

          Package Files (1)

          Dependencies (1)

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