cvazac

window.addEventListener('load', function() {
  let totalBytesSaved = 0
  for (const {encodedBodySize, serverTiming} of performance.getEntriesByType('resource')) {
    for (const {name, description} of serverTiming || []) {
      if (name === 'disk') {
        totalBytesSaved += parseInt(description) - encodedBodySize
      }
    }
  }
  console.info('Total Bytes Saved:', totalBytesSaved)

cvazac

function wasServedFromBrowserCache(url) {
  const {transferSize, decodedBodySize, duration} = performance.getEntriesByName(url)[0]
  
  // if we transferred bytes, it must not be a cache hit
  // (will return false for 304 Not Modified)
  if (transferSize > 0) return false;

  // if the body size is non-zero, it must mean this is a
  // ResourceTiming2 browser, this was same-origin or TAO,
  // and transferSize was 0, so it was in the cache

cvazac

const applyBind = Function.prototype.bind.bind(Function.prototype.apply);
const mapSetApply = applyBind(Map.prototype.set);
const hijackedFns = new Map();
function hijackFunction(context, propName, replacer) {
    mapSetApply(hijackedFns, [replacer, context[propName]]);
    context[propName] = replacer;
}
const fnToStringApply = applyBind(Function.prototype.toString);
const mapGetApply = applyBind(Map.prototype.get);
hijackFunction(Function.prototype, 'toString', function toString() {