lighthouse-plugin-green-it
Version:
plugin for lighthouse that uses Eco index's calculation methods to give a green it score
144 lines (135 loc) • 7.49 kB
JavaScript
const Audit = require('lighthouse').Audit;
const NetworkRequest = require('lighthouse/lighthouse-core/lib/network-request.js');
const NetworkRecords = require('lighthouse/lighthouse-core/computed/network-records.js');
class GreenItAudit extends Audit {
static get meta() {
return {
id: 'greenit-audit',
title: 'Page is eco-friendly',
description: 'Check if the page is optimized for eco-friendly practices.',
requiredArtifacts: ['DOMStats', 'devtoolsLogs'],
failureTitle: 'Page is not eco-friendly'
};
}
static async audit(artifacts, context) {
const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
try {
const networkRecords = await NetworkRecords.request(devtoolsLog, context);
const domSize = artifacts.DOMStats.totalBodyElements;
const totalPageSize = +((networkRecords.reduce((totalSize, record) => totalSize + record.transferSize, 0)) / 1000).toFixed(1);
const numberOfRequests = networkRecords.length;
const results = analyzeWebCarbon({ 'dom': domSize, 'req': numberOfRequests, 'size': totalPageSize });
/*
The EcoIndex scoring algorithm has been adjusted in this context to address perceived shortcomings in its original form.
The initial approach appeared to disproportionately penalize scores based on the quantity of DOM elements.
This adjustment is aimed at rectifying this perceived imbalance.
A key requirement of this modification was to ensure that it had no impact on the calculations for CO2 emissions and water usage.
As such, the modification involves a simple addition of 10 points to the score.
This adjustment is justified with the case study of a webpage such as 'example.com'.
Despite its efficient characteristics of this page, such as a weight of 1kb, the presence of only 5 DOM elements, and a single request,
the original EcoIndex scoring failed to award it the optimal score of 100. This modification seeks to address and correct such instances.
*/
const details = {
type: 'table',
headings: [
{ key: 'field', itemType: 'text', text: 'Measurement' },
{ key: 'value', itemType: 'text', text: 'Value' },
],
items: [
{ field: 'Grade', value: results.grade },
{ field: 'Greenhouse Gas Emissions (per 1000 visits)', value: `${results.ghg} kgC02e` },
{ field: 'Water Consumption (per 1000 visits)', value: `${results.water} L` },
],
};
return {
score: results.score / 100,
numericValue: results.score / 100,
details: details,
};
} catch (error) {
console.error(`Failed to get network records: ${error}`);
throw error;
}
}
}
module.exports = GreenItAudit;
/**
* Analyzes the web carbon metrics and returns related data.
*
* @param {Object} metrics - The metrics containing dom, req, and size.
* @returns {Object} An object containing the dom, requests, size, ecoIndex score, grade, greenhouse gases, and water consumption.
*/
function analyzeWebCarbon(metrics) {
const domSize = metrics.dom;
const totalRequests = metrics.req;
const totalPageSize = metrics.size;
const ecoIndex = +(computeEcoIndex(domSize, totalRequests, totalPageSize)).toFixed(0);
const mod_ecoIndex = ecoIndex + 10 > 100 ? 100 : ecoIndex + 10;
const grade = getEcoIndexGrade(mod_ecoIndex);
const ghg = computeGreenhouseGasesEmissionfromEcoIndex(ecoIndex);
const water = computeWaterConsumptionfromEcoIndex(ecoIndex);
return { dom: domSize, requests: totalRequests, size: totalPageSize, score: mod_ecoIndex, grade: grade, ghg: ghg, water: water };
}
/**
* Computes Eco Index based on given DOM, requests and page size.
*
* @param {number} dom - The number of DOM elements.
* @param {number} req - The number of requests.
* @param {number} size - The page size in kB.
* @returns {number} - The computed Eco Index.
*/
function computeEcoIndex(dom, req, size) {
const quantiles_dom = [0, 47, 75, 159, 233, 298, 358, 417, 476, 537, 603, 674, 753, 843, 949, 1076, 1237, 1459, 1801, 2479, 594601];
const quantiles_req = [0, 2, 15, 25, 34, 42, 49, 56, 63, 70, 78, 86, 95, 105, 117, 130, 147, 170, 205, 281, 3920];
const quantiles_size = [0, 1.37, 144.7, 319.53, 479.46, 631.97, 783.38, 937.91, 1098.62, 1265.47, 1448.32, 1648.27, 1876.08, 2142.06, 2465.37, 2866.31, 3401.59, 4155.73, 5400.08, 8037.54, 223212.26];
const q_dom = computeQuantile(quantiles_dom, dom);
const q_req = computeQuantile(quantiles_req, req);
const q_size = computeQuantile(quantiles_size, size);
return 100 - 5 * (3 * q_dom + 2 * q_req + q_size) / 6;
}
/**
* Computes the quantile for a given value within a set of quantiles.
*
* @param {number[]} quantiles - The set of quantiles.
* @param {number} value - The value to find the quantile for.
* @returns {number} - The computed quantile.
*/
function computeQuantile(quantiles, value) {
for (let i = 1; i < quantiles.length; i++) {
if (value < quantiles[i]) return (i - 1 + (value - quantiles[i - 1]) / (quantiles[i] - quantiles[i - 1]));
}
return quantiles.length - 1;
}
/**
* Maps an Eco Index score to a grade (A - G).
*
* @param {number} ecoIndex - The Eco Index score.
* @returns {string} - The corresponding grade.
*/
function getEcoIndexGrade(ecoIndex) {
if (ecoIndex >= 90) return "A";
if (ecoIndex >= 75) return "B";
if (ecoIndex >= 55) return "C";
if (ecoIndex >= 40) return "D";
if (ecoIndex >= 25) return "E";
if (ecoIndex >= 10) return "F";
return "G";
}
/**
* Computes greenhouse gases emission from an Eco Index score.
*
* @param {number} ecoIndex - The Eco Index score.
* @returns {number} - The computed greenhouse gases emission in kg for 1000 visits.
*/
function computeGreenhouseGasesEmissionfromEcoIndex(ecoIndex) {
return (2 + 2 * (50 - ecoIndex) / 100).toFixed(2); // kg for 1000 visits
}
/**
* Computes water consumption from an Eco Index score.
*
* @param {number} ecoIndex - The Eco Index score.
* @returns {number} - The computed water consumption in L for 1000 visits.
*/
function computeWaterConsumptionfromEcoIndex(ecoIndex) {
return ((3 + 3 * (50 - ecoIndex) / 100) * 10).toFixed(2); // L for 1000 visits
}