Neptune's Potato Monsters


    2.4.2 • Public • Published


    Louis is a gulp task that is used to analyze the performance of a website against a performance budget.

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    There are many definitions of the performance budget on the web, my favourite is from Zachary Brady.

    A performance budget provides values against which design, development, content, or any aspect of a site that may affect performance, can be made.

    The aim of the plugin is to analyze the performance of the website against a performance bugdet. There are various metrics against which we can set a performance budget e.g. number of requests, imageSize etc.

    Getting started


    1. Usage

    2. Example

    3. Output

    4. Options

    5. Performance Budget Options

    6. Change log

    Getting Started


    $ npm install --save-dev gulp-louis
    import louis = require('gulp-louis');
    gulp.task('louis', function(done) {
        timeout: 60,
        viewport: '1280x1024',
        engine: 'webkit',
        userAgent: 'Chrome/37.0.2062.120',
        noExternals: false,
        performanceBudget: {
          requests: 2,
          medianLatency: 10,
          slowestResponse: 1000
      }, done);
    gulp.task('default', ['louis']);


    Example 1 (with specified url)

      url: 'http://localhost:8000/',
      timeout: 200,
      performanceBudget: {
        requests: 10,
        domComplete: 3000

    Example 2 (without url) This will launch a server and look for an index.html in the same folder as the gulpfile.js, then it will analyze the performance of this website.

      timeout: 10,
      performanceBudget: {
        requests: 10,
        headersSize: 200


    Output with specified performance budget


    Output without specified performance budget



    All options are optional

    • url url of the website to be analyzed, if it is not specified Louis will launch a server and load the index.html if this exist on the same directory as the gulpfile.js
    • timeout timeout for the run (defaults to 15 seconds)
    • viewport dimensions ('1280x1024' is the default)
    • engine webkit or gecko (webkit is default)
    • userAgent default is Chrome/37.0.2062.120
    • noExternals true or false, default is false, block requests to 3rd party domains
    • outputFileName name of file to write the results, default is "results.json"
    • performanceBudget object with metrics, see below
    • proxy specifies the (optional) proxy server to use

    Performance Budget Options

    The performance budget option can contain some or all of these values:

    requests, gzipRequests, postRequests, httpsRequests, notFound, bodySize, contentLength, httpTrafficCompleted, timeToFirstByte, timeToLastByte, ajaxRequests, htmlCount, htmlSize, cssCount, cssSize, jsCount, jsSize, jsonCount, jsonSize, imageCount, imageSize, videoCount, videoSize, webfontCount, webfontSize, base64Count, base64Size, otherCount, otherSize, cacheHits, cacheMisses, cachePasses, cachingNotSpecified, cachingTooShort, cachingDisabled, oldCachingHeaders, consoleMessages, cookiesSent, cookiesRecv, domainsWithCookies, documentCookiesLength, documentCookiesCount, documentHeight, commentsSize, whiteSpacesSize, DOMelementsCount, DOMelementMaxDepth, nodesWithInlineCSS, imagesScaledDown, imagesWithoutDimensions, DOMidDuplicated, hiddenContentSize, DOMmutationsInsertsv, DOMmutationsRemoves, DOMmutationsAttributes, DOMqueries, DOMqueriesWithoutResults, DOMqueriesById, DOMqueriesByClassName, DOMqueriesByTagName, DOMqueriesByQuerySelectorAll , DOMinserts, DOMqueriesDuplicated, DOMqueriesAvoidable, domains, maxRequestsPerDomain, medianRequestsPerDomain, eventsBound, eventsDispatched, globalVariables, globalVariablesFalsy, headersCount, headersSentCount, headersRecvCount, headersSize, headersSentSize, headersRecvSize, headersBiggerThanContent, jQueryVersion, jQueryVersionsLoaded, jQueryOnDOMReadyFunctions, jQueryWindowOnLoadFunctions, jQuerySizzleCalls, jQueryEventTriggers, jQueryDOMReads, jQueryDOMWrites, jQueryDOMWriteReadSwitches, documentWriteCalls, evalCalls, jsErrors, closedConnections, localStorageEntries, redirects, redirectsTime, repaints, firstPaint, requestsToDomContentLoaded, requestsToDomComplete, assetsNotGzipped, assetsWithQueryString, assetsWithCookies, smallImages, smallCssFiles, smallJsFiles, multipleRequests, timeToFirstCss, timeToFirstJs, timeToFirstImage, domInteractive, domContentLoaded, domContentLoadedEnd, domComplete, timeBackend, timeFrontend, statusCodesTrail, windowAlerts, windowConfirms, windowPrompts, bodyHTMLSize, iframesCount, smallestResponse, biggestResponse, fastestResponse, slowestResponse, smallestLatency, biggestLatency, medianResponse, medianLatency


    performanceBudget = {
      cssSize: 200
      jsSize: 2000
      consoleMessages: 0
      imageSize: 5000
      domContentLoaded: 2000
      smallestLatency: 1000

    Change log

    [2.3.2] - 2018-03-16

    • Fix / appended to outputFile causing throw in unix systems

    [2.3.1] - 2018-02-28

    • Update dependencies

    [2.3.0] - 2016-10-07

    • Added proxy-option

    [2.2.1] - 2016-09-29

    • Update dependencies

    [2.2.0] - 2016-09-29

    • Add outputFilename-option

    [2.1.1] - 2016-09-16

    • Update dependencies

    [2.1.0] - 2016-09-15

    • Change the results.json to a file with the same of tested domain.

    [2.0.0] - 2016-08-29

    • Run phantomas from local path
    • Update depedencies

    [1.1.0] - 2016-08-19

    • Fix phantomas path

    [1.0.14] - 2015-11-23

    Bug Fixes

    • Fix path to phantomas command …

    • Add missing gulp-connect dependency

    • Change "main" script to "louis.js"

    [1.0.10] - 2015-02-21

    [1.0.9] - 2015-02-21

    [1.0.8] - 2015-02-20

    [1.0.7] - 2015-02-17

    [1.0.0] - 2015-02-16


    Released under the MIT license.


    npm i gulp-louis

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    • avrmav