compression | Node.js compression middleware | Compression library

 by   expressjs JavaScript Version: 1.7.3 License: MIT

kandi X-RAY | compression Summary

kandi X-RAY | compression Summary

compression is a JavaScript library typically used in Utilities, Compression, Nodejs, Express.js applications. compression has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. You can install using 'npm i comprex' or download it from GitHub, npm.

The following compression codings are supported:.

            kandi-support Support

              compression has a medium active ecosystem.
              It has 2645 star(s) with 237 fork(s). There are 54 watchers for this library.
              It had no major release in the last 12 months.
              There are 12 open issues and 124 have been closed. On average issues are closed in 38 days. There are 18 open pull requests and 0 closed requests.
              It has a neutral sentiment in the developer community.
              The latest version of compression is 1.7.3

            kandi-Quality Quality

              compression has 0 bugs and 0 code smells.

            kandi-Security Security

              compression has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              compression code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              compression is licensed under the MIT License. This license is Permissive.
              Permissive licenses have the least restrictions, and you can use them in most projects.

            kandi-Reuse Reuse

              compression releases are available to install and integrate.
              Deployable package is available in npm.
              Installation instructions, examples and code snippets are available.

            Top functions reviewed by kandi - BETA

            kandi has reviewed compression and discovered the below as its top functions. This is intended to give you an instant insight into compression implemented functionality, and help decide if they suit your requirements.
            • Compose a compression response .
            Get all kandi verified functions for this library.

            compression Key Features

            No Key Features are available at this moment for compression.

            compression Examples and Code Snippets

            WebSocket compression
            npmdot img1Lines of Code : 29dot img1no licencesLicense : No License
            copy iconCopy
            import WebSocket, { WebSocketServer } from 'ws';
            const wss = new WebSocketServer({
              port: 8080,
              perMessageDeflate: {
                zlibDeflateOptions: {
                  // See zlib defaults.
                  chunkSize: 1024,
                  memLevel: 7,
                  level: 3
            npmdot img2Lines of Code : 15dot img2no licencesLicense : No License
            copy iconCopy
            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 respo  
            Creates a compact topic with compression codec .
            javadot img3Lines of Code : 21dot img3License : Permissive (MIT License)
            copy iconCopy
            public void createCompactedTopicWithCompression(String topicName) throws Exception {
                    Properties props = new Properties();
                    props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
                    try (Admin admin = Admin.creat  
            Finds the closest path compression for the given node .
            javadot img4Lines of Code : 11dot img4License : Permissive (MIT License)
            copy iconCopy
            private Integer pathCompressionFind(Integer node) {
                    DisjointSetInfo setInfo = nodes.get(node);
                    Integer parent = setInfo.getParentNode();
                    if (parent.equals(node)) {
                        return node;
                    } else {
            Validate the compression argument .
            pythondot img5Lines of Code : 5dot img5License : Non-SPDX (Apache License 2.0)
            copy iconCopy
            def _validate_compression(compression):
              valid_compressions = [COMPRESSION_AUTO, COMPRESSION_NONE]
              if compression not in valid_compressions:
                raise ValueError(f"Invalid `compression` argument: {compression}. "
                                 f"Must be one  

            Community Discussions


            Fixing git HTTPS Error: "bad key length" on macOS 12
            Asked 2022-Mar-29 at 17:34

            I am using a company-hosted (Bitbucket) git repository that is accessible via HTTPS. Accessing it (e.g. git fetch) worked using macOS 11 (Big Sur), but broke after an update to macOS 12 Monterey. *

            After the update of macOS to 12 Monterey my previous git setup broke. Now I am getting the following error message:



            Answered 2021-Nov-02 at 07:12

            Unfortunately I can't provide you with a fix, but I've found a workaround for that exact same problem (company-hosted bitbucket resulting in exact same error). I also don't know exactly why the problem occurs, but my best guess would be that the libressl library shipped with Monterey has some sort of problem with specific (?TLSv1.3) certs. This guess is because the brew-installed openssl v1.1 and v3 don't throw that error when executed with /opt/homebrew/opt/openssl/bin/openssl s_client -connect ...:443

            To get around that error, I've built git from source built against different openssl and curl implementations:

            1. install autoconf, openssl and curl with brew (I think you can select the openssl lib you like, i.e. v1.1 or v3, I chose v3)
            2. clone git version you like, i.e. git clone --branch v2.33.1
            3. cd git
            4. make configure (that is why autoconf is needed)
            5. execute LDFLAGS="-L/opt/homebrew/opt/openssl@3/lib -L/opt/homebrew/opt/curl/lib" CPPFLAGS="-I/opt/homebrew/opt/openssl@3/include -I/opt/homebrew/opt/curl/include" ./configure --prefix=$HOME/git (here LDFLAGS and CPPFLAGS include the libs git will be built against, the right flags are emitted by brew on install success of curl and openssl; --prefix is the install directory of git, defaults to /usr/local but can be changed)
            6. make install
            7. ensure to add the install directory's subfolder /bin to the front of your $PATH to "override" the default git shipped by Monterey
            8. restart terminal
            9. check that git version shows the new version

            This should help for now, but as I already said, this is only a workaround, hopefully Apple fixes their libressl fork ASAP.



            git gc: error: Could not read 0000000000000000000000000000000000000000
            Asked 2022-Mar-28 at 14:18
            git gc
            error: Could not read 0000000000000000000000000000000000000000
            Enumerating objects: 147323, done.
            Counting objects: 100% (147323/147323), done.
            Delta compression using up to 4 threads
            Compressing objects: 100% (36046/36046), done.
            Writing objects: 100% (147323/147323), done.
            Total 147323 (delta 91195), reused 147323 (delta 91195), pack-reused 0


            Answered 2022-Mar-28 at 14:18

            This error is harmless in the sense that it does not indicate a broken repository. It is a bug that was introduced in Git 2.35 and that should be fixed in later releases.

            The worst that can happen is that git gc does not prune all objects that are referenced from reflogs. The error is triggered by an invocation of git reflog expire --all that git gc does behind the scenes.

            The trigger are empty reflog files in the .git/logs directory structure that were left behind after a branch was deleted. As a workaround you can remove these empty files. This command lets you find them and check their size:



            Vuejs Webpack Compression Plugin not compressing
            Asked 2022-Mar-28 at 12:53

            I need help debugging Webpack's Compression Plugin.


            • Goal is to enable asset compression and reduce my app's bundle size. Using the Brotli algorithm as the default, and gzip as a fallback for unsupported browsers.
            • I expected a content-encoding field within an asset's Response Headers. Instead, they're loaded without the field. I used the Chrome dev tools' network tab to confirm this. For context, see the following snippet:
            • No errors show in my browser or IDE when running locally.

            WHAT I TRIED

            • Using different implementations for the compression plugin. See below list of approaches:
              1. (With Webpack Chain API)


            Answered 2021-Sep-30 at 14:59

            It's not clear which server is serving up these assets. If it's Express, looking at the screenshot with the header X-Powered-By, shows that Brotli support hasn't been added to Express yet.

            There might be a way to just specify the header for content-encoding manually though.



            Is Shannon-Fano coding ambiguous?
            Asked 2022-Mar-08 at 19:38
            In a nutshell:

            Is the Shannon-Fano coding as described in Fano's paper The Transmission of Information (1952) really ambiguous?

            In Detail:

            3 papers
            Claude E. Shannon published his famous paper A Mathematical Theory of Communication in July 1948. In this paper he invented the term bit as we know it today and he also defined what we call Shannon entropy today. And he also proposed an entropy based data compression algorithm in this paper. But Shannon's algorithm was so weak, that under certain circumstances the "compressed" messages could be even longer than in fix length coding. A few month later (March 1949) Robert M. Fano published an improved version of Shannons algorithm in the paper The Transmission of Information. 3 years after Fano (in September 1952) his student David A. Huffman published an even better version in his paper A Method for the Construction of Minimum-Redundancy Codes. Hoffman Coding is more efficient than its two predecessors and it is still used today. But my question is about the algorithm published by Fano which usually is called Shannon-Fano-Coding.

            The algorithm
            This description is based on the description from Wikipedia. Sorry, I did not fully read Fano's paper. I only browsed through it. It is 37 pages long and I really tried hard to find a passage where he talks about the topic of my question, but I could not find it. So, here is how Shannon-Fano encoding works:

            1. Count how often each character appears in the message.
            2. Sort all characters by frequency, characters with highest frequency on top of the list
            3. Divide the list into two parts, such that the sums of frequencies in both parts are as equal as possible. Add the bit 0 to one part and the bit 1 to the other part.
            4. Repeat step 3 on each part that contains 2 or more characters until all parts consist of only 1 character.
            5. Concatenate all bits from all rounds. This is the Shannon-Fano-code of that character.

            An example
            Let's execute this on a really tiny example (I think it's the smallest message where the problem appears). Here is the message to encode:



            Answered 2022-Mar-08 at 19:00

            To directly answer your question, without further elaboration about how to break ties, two different implementations of Shannon-Fano could produce different codes of different lengths for the same inputs.

            As @MattTimmermans noted in the comments, Shannon-Fano does not always produce optimal prefix-free codings the way that, say, Huffman coding does. It might therefore be helpful to think of it less as an algorithm and more of a heuristic - something that likely will produce a good code but isn't guaranteed to give an optimal solution. Many heuristics suffer from similar issues, where minor tweaks in the input or how ties are broken could result in different results. A good example of this is the greedy coloring algorithm for finding vertex colorings of graphs. The linked Wikipedia article includes an example in which changing the order in which nodes are visited by the same basic algorithm yields wildly different results.

            Even algorithms that produce optimal results, however, can sometimes produce different optimal results based on tiebreaks. Take Huffman coding, for example, which works by repeatedly finding the two lowest-weight trees assembled so far and merging them together. In the event that there are three or more trees at some intermediary step that are all tied for the same weight, different implementations of Huffman coding could produce different prefix-free codes based on which two they join together. The resulting trees would all be equally "good," though, in that they'd all produce outputs of the same length. (That's largely because, unlike Shannon-Fano, Huffman coding is guaranteed to produce an optimal encoding.)

            That being said, it's easy to adjust Shannon-Fano so that it always produces a consistent result. For example, you could say "in the event of a tie, choose the partition that puts fewer items into the top group," at which point you would always consistently produce the same coding. It wouldn't necessarily be an optimal encoding, but, then again, since Shannon-Fano was never guaranteed to do so, this is probably not a major concern.

            If, on the other hand, you're interested in the question of "when Shannon-Fano has to break a tie, how do I decide how to break the tie to produce the optimal solution?," then I'm not sure of a way to do this other than recursively trying both options and seeing which one is better, which in the worst case leads to exponentially-slow runtimes. But perhaps someone else here can find a way to do that>



            Why does this .c file #include itself?
            Asked 2022-Feb-18 at 07:48

            Why does this .c file #include itself?




            Answered 2022-Feb-18 at 07:48

            The file includes itself so the same source code can be used to generate 4 different sets of functions for specific values of the macro USIZE.

            The #include directives are actually enclosed in an #ifndef, which limits the recursion to a single level:



            APL Fork/Train with Compression
            Asked 2022-Feb-18 at 07:42

            I want to select elements from an array based on some test. Currently, I am trying to do that with a compression, and I would like to write it as a tacit function. (I'm very new to APL, so feel free to suggest other options.) Below is a minimal (not-)working example.

            The third line below shows that I can use the testing function f on vec and then do the compression, and the fifth line shows I can apply the identity function to vec (as expected). So based on my understanding of the train documentation, I should be able to make a fork from f and with / as the center prong. Below shows that this does not work, and I presume it is because Dyalog is interpreting the sixth and eighth lines as doing an f-reduce. Is there a way to indicate that I want a compression train and not a reduce? (and/or is there a better way to do this altogether?)



            Answered 2022-Feb-18 at 07:42

            Yes, by making / an operand, it is forced to behave as a function. As per APL Wiki, applying atop the result of / solves the problem:



            .NET 6 failing at Decompress large gzip text
            Asked 2022-Feb-01 at 10:43

            I have to decompress some gzip text in .NET 6 app, however, on a string that is 20,627 characters long, it only decompresses about 1/3 of it. The code I am using code works for this string in .NET 5 or .NETCore 3.1 As well as smaller compressed strings.



            Answered 2022-Feb-01 at 10:43

            Just confirmed that the article linked in the comments below the question contains a valid clue on the issue.

            Corrected code would be:



            angular 13: Module not found: Error: Can't resolve 'rxjs/operators'
            Asked 2022-Jan-22 at 05:29

            I have upgraded my angular to angular 13. when I run to build SSR it gives me following error.



            Answered 2022-Jan-22 at 05:29

            I just solve this issue by correcting the RxJS version to 7.4.0. I hope this can solve others issue as well.



            JavaScript: V8 question: are small integers pooled?
            Asked 2022-Jan-17 at 12:37

            was looking at this V8 design doc where it has a section for Constant Pool Entries

            it says

            Constant pools are used to store heap objects and small integers that are referenced as constants in generated bytecode. and

            ... Small integers and the strong referenced oddball type’s have bytecodes to load them directly and do not go into the constant pool.

            So I am confused: are small integers pooled or not?

            My understanding is that it is not worth it pooling small integers if sizeof(int) < sizeof(int *) - because it is cheaper to just copy the actual integer instead of copying the pointer that points to the integer in the constant pool. Also variables that hold integers can be optimised to be stored directly in CPU registers and skip being allocated in memory first.

            Also, are they located on the V8 heap or the stack? My understanding had always been that smis are just be the immediate values allocated on the stack instead of being a pointer + an integer allocated on heap. Also if you take a heap snapshot using chrome devtool you cannot find smis in the heap snapshot - only heap number such as big integers or double like 3.14 are on the heap until I saw this article

            JavaScript values in V8 are represented as objects and allocated on the V8 heap, no matter if they are objects, arrays, numbers or strings. This allows us to represent any value as a pointer to an object.

            Now I am just baffled - are smis also allocated on the heap?



            Answered 2022-Jan-17 at 12:37

            V8 developer here.

            are small integers pooled or not?

            They are not (at least not right now). That said, this is a small implementation detail and could be done either way: it would totally be possible to use the constant pool for Smis. I suppose the decision to build special machinery for Smis (instead of reusing the general-purpose constant pool) was made because things turned out to be more efficient that way.

            it is not worth it pooling small integers if sizeof(int) < sizeof(int *)

            The details are different (a Smi is not an int, and constant pool slots are referenced by index rather than C++ pointer), but this reasoning does go in the right direction: avoiding indirections can save time and memory.

            are smis also allocated on the heap?

            Yes, everything is allocated on the heap. The stack is only useful for temporary (and sufficiently small) things; that's largely unrelated to the type of thing.

            The "trick" of Smis is that they're not stored as separate objects: when you have an object that refers to a Smi, such as let foo = {smi: 42}, then the value 42 can be smi-encoded and stored directly inside the "foo" object (whereas if the value was 42.5, then the object would store a pointer to a separate "HeapNumber"). But since the object is on the heap, so is the Smi.


            What I understand [...] is that constant small integers are pooled. Variable small integers are not.

            Nope. Any literal that occurs in source code is "constant". Whether you use let or const for your variables has nothing to do with this.



            Paramiko authentication fails with "Agreed upon 'rsa-sha2-512' pubkey algorithm" (and "unsupported public key algorithm: rsa-sha2-512" in sshd log)
            Asked 2022-Jan-13 at 14:49

            I have a Python 3 application running on CentOS Linux 7.7 executing SSH commands against remote hosts. It works properly but today I encountered an odd error executing a command against a "new" remote server (server based on RHEL 6.10):

            encountered RSA key, expected OPENSSH key

            Executing the same command from the system shell (using the same private key of course) works perfectly fine.

            On the remote server I discovered in /var/log/secure that when SSH connection and commands are issued from the source server with Python (using Paramiko) sshd complains about unsupported public key algorithm:

            userauth_pubkey: unsupported public key algorithm: rsa-sha2-512

            Note that target servers with higher RHEL/CentOS like 7.x don't encounter the issue.

            It seems like Paramiko picks/offers the wrong algorithm when negotiating with the remote server when on the contrary SSH shell performs the negotiation properly in the context of this "old" target server. How to get the Python program to work as expected?

            Python code



            Answered 2022-Jan-13 at 14:49

            Imo, it's a bug in Paramiko. It does not handle correctly absence of server-sig-algs extension on the server side.

            Try disabling rsa-sha2-* on Paramiko side altogether:


            Community Discussions, Code Snippets contain sources that include Stack Exchange Network


            No vulnerabilities reported

            Install compression

            This is a Node.js module available through the npm registry. Installation is done using the npm install command:.


            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
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