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    1.7.0 • Public • Published


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    What is this?

    This npm package provides an ExpressJS middleware that sets the request object with a version property by parsing a request HTTP header.


    Set request version statically

    If you wish to employ your own logic in some middleware/configuration and set the request version programmaticaly and not by parsing a specific HTTP header:

    const versionRequest = require('express-version-request')

    Then in later middlewares you will be able to access req.version property and it's value set to 1.2.3.

    Set request version by HTTP header

    By default, the library will parse the version out of the X-Api-Version HTTP header:

    const versionRequest = require('express-version-request')

    Set request version by custom HTTP header

    If you wish to advise the library which HTTP header to parse to extract the version:

    const versionRequest = require('express-version-request')

    Set request version by HTTP query parameter

    By default, the library will parse the version out of the api-version query parameter:

    const versionRequest = require('express-version-request')

    Set request version by custom HTTP query parameter

    If you wish to advise the library which query parameter to parse to extract the version:

    const versionRequest = require('express-version-request')

    setVersionByQueryParam options

    The second parameter of setVersionByQueryParam is an options object.

    Set request version by 'Accept' header

    By default, the library will parse the version from the Accept header, expecting the following format: Accept: application/;version=1.0.0 For more details about the Accept header format, please refer to the RFC.

    const versionRequest = require('express-version-request')

    Parsing using an alternative format

    As a fallback, the lib supports an alternative Accept header format:

    Accept: application/vnd.comapny-v1.0.0+json


    Accept: application/vnd.comapny.v1.0.0+json

    The lib will try to parse the header using the default format, and if it doesn't succeed, tries this alternative format. The usage is the same as in the case of the regular format:

    const versionRequest = require('express-version-request')

    Parsing using a custom function

    If you wish to use your own parsing, it is possible to pass a function as the first parameter. The lib will then call it with the actual value of the Accept header as the first parameter, and the returned value will be set as version. The provided function should return a string.

    const versionRequest = require('express-version-request')
    function customParsingFunction(header) {
        //function body, that parses the header parameter and returns a string

    Version formatting

    Before setting the version, it is always formatted, so the resulting version is a semver comaptible string, except the following cases:

    • if the version was set as an Object, it will be returned in stringified format (using JSON.stringify)
    • if the version is longer than the semver format, we truncate it by cutting off the tail, and leaving the first three segments (e.g.: will become 1.2.3)
    • if we encunter something, that can't be parsed or formatted as a version, undefined is returned

    This formatting function is called automatically for each version setting method, but it can also be used independently:

    const versionRequest = require('express-version-request')
    const formattedVersion = versionRequest.formatVersion(versionThatNeedsFormatting)


    Delete version HTTP query parameter after setting the request object with a version property. By default it is set to false.

    const versionRequest = require('express-version-request')
    const options = {removeQueryParam: true}
    app.use(versionRequest.setVersionByQueryParam('myQueryParam', options))

    If you define a middleware after versionRequest then you can verify that the version is indeed set:

    app.use((req, res, next) => {


    yarn add express-version-request


    yarn test

    Project linting:

    yarn lint


    yarn test:coverage


    The project uses the commitizen tool for standardizing changelog style commit messages so you should follow it as so:

    git add .           # add files to staging 
    yarn commit      # use the wizard for the commit message 


    Liran Tal


    npm i express-version-request

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