coach-core/lib/dom/bestpractice/optimizely.js

Core package for the Coach.

(function (util) {
  'use strict';

  const scripts = util.getSynchJSFiles(document.head);
  const offending = [];
  let score = 100;
  let advice = '';

  for (const script of scripts) {
    if (util.getHostname(script) === 'cdn.optimizely.com') {
      offending.push(script);
      score = 0;
      advice =
        'The page is using Optimizely. Use it with care because it hurts your performance. Only turn it on (= load the JavaScript) when you run your A/B tests. Then when you are finished make sure to turn it off.';
    }
  }

  return {
    id: 'optimizely',
    title: 'Only use Optimizely when you need it',
    description:
      'Use Optimizely with care because it hurts your performance since JavaScript is loaded synchronously inside of the head tag, making the first paint happen later. Only turn on Optimzely (= load the javascript) when you run your A/B tests.',
    advice: advice,
    score: score,
    weight: 2,
    severity: 'info',
    offending: offending,
    tags: ['bestpractice']
  };
})(util);