analyseFrameWithBestPractices.js

/*
 *  Copyright (C) 2016  The EcoMeter authors (https://gitlab.com/ecoconceptionweb/ecometer)
 *  Copyright (C) 2019-2022  didierfred@gmail.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published
 *  by the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

function start_analyse() {
  const analyseStartingTime = Date.now();
  const dom_size = getDomSizeWithoutSvg();
  // test with http://www.wickham43.net/flashvideo.php
  const pluginsNumber = getPluginsNumber();
  const printStyleSheetsNumber = getPrintStyleSheetsNumber();
  const inlineStyleSheetsNumber = getInlineStyleSheetsNumber();
  const inlineJsScript = getInlineJsScript();
  const inlineJsScriptsNumber = getInlineJsScriptsNumber();
  const imagesResizedInBrowser = getImagesResizedInBrowser();
  const pageAnalysis = {
    analyseStartingTime: analyseStartingTime,
    url: document.URL,
    domSize: dom_size,
    pluginsNumber: pluginsNumber,
    printStyleSheetsNumber: printStyleSheetsNumber,
    inlineStyleSheetsNumber: inlineStyleSheetsNumber,
    inlineJsScript: inlineJsScript,
    inlineJsScriptsNumber: inlineJsScriptsNumber,
    imagesResizedInBrowser: imagesResizedInBrowser,
  };

  chrome.runtime.sendMessage(pageAnalysis);
}

function getDomSizeWithoutSvg() {
  let dom_size = document.getElementsByTagName("*").length;
  const svgElements = document.getElementsByTagName("svg");
  for (let i = 0; i < svgElements.length; i++) {
    dom_size -= getNbChildsExcludingNestedSvg(svgElements[i]) - 1;
  }
  return dom_size;
}

function getNbChildsExcludingNestedSvg(element) {
  if (element.nodeType === Node.TEXT_NODE) return 0;
  let nb_elements = 1;
  for (let i = 0; i < element.childNodes.length; i++) {
    // deal with svg nested case
    if (element.childNodes[i].tagName !== "svg")
      nb_elements += getNbChildsExcludingNestedSvg(element.childNodes[i]);
    else nb_elements += 1;
  }
  return nb_elements;
}

function getPluginsNumber() {
  const plugins = document.querySelectorAll("object,embed");
  return plugins === undefined ? 0 : plugins.length;
}

function getPrintStyleSheetsNumber() {
  return (
    document.querySelectorAll("link[rel=stylesheet][media~=print]").length +
    document.querySelectorAll("style[media~=print]").length
  );
}

function getInlineStyleSheetsNumber() {
  let styleSheetsArray = Array.from(document.styleSheets);
  let inlineStyleSheetsNumber = 0;
  styleSheetsArray.forEach((styleSheet) => {
    try {
      // Ignore SVG styles in count
      const isSvgStyleSheet = styleSheet.ownerNode instanceof SVGStyleElement;
      if (!styleSheet.href && !isSvgStyleSheet) inlineStyleSheetsNumber++;
    } catch (err) {
      console.log("GREENIT-ANALYSIS ERROR ," + err.name + " = " + err.message);
      console.log("GREENIT-ANALYSIS ERROR " + err.stack);
    }
  });
  return inlineStyleSheetsNumber;
}

function getInlineJsScript() {
  let scriptArray = Array.from(document.scripts);
  let scriptText = "";
  scriptArray.forEach((script) => {
    let isJSON = String(script.type) === "application/ld+json"; // Exclude type="application/ld+json" from parsing js analyse
    if (script.text.length > 0 && !isJSON) scriptText += "\n" + script.text;
  });
  return scriptText;
}

function getInlineJsScriptsNumber() {
  let scriptArray = Array.from(document.scripts);
  let inlineScriptNumber = 0;
  scriptArray.forEach((script) => {
    let isJSON = String(script.type) === "application/ld+json"; // Exclude type="application/ld+json" from count
    if (script.text.length > 0 && !isJSON) inlineScriptNumber++;
  });
  return inlineScriptNumber;
}

function getImagesResizedInBrowser() {
  const imgArray = Array.from(document.querySelectorAll("img"));
  let imagesResized = [];
  imgArray.forEach((img) => {
    if (
      img.clientWidth < img.naturalWidth ||
      img.clientHeight < img.naturalHeight
    ) {
      // Images of one pixel are some times used ... , we exclude them
      if (img.naturalWidth > 1) {
        const imageMeasures = {
          src: img.src,
          clientWidth: img.clientWidth,
          clientHeight: img.clientHeight,
          naturalWidth: img.naturalWidth,
          naturalHeight: img.naturalHeight,
        };
        imagesResized.push(imageMeasures);
      }
    }
  });
  return imagesResized;
}

start_analyse();