finalizationRegistry_worker.js

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let holdings1 = [];

let holdings2 = [];

let holdings3 = [];

let holdings4 = [];

let holdings5 = [];

onmessage = (event) => {

  switch (event.data) {

  case 'startTest':

    startTest();

    break;

  case 'checkResults':

    checkResults();

    break;

  default:

    throw "Unknown message";

};

function startTest() {

  // Registry with no registered objects.

  let registry1 = new FinalizationRegistry(v => { holdings1.push(v); });

  // Registry with three registered objects.

  let registry2 = new FinalizationRegistry(v => { holdings2.push(v); });

  registry2.register({}, 1);

  registry2.register({}, 2);

  registry2.register({}, 3);

  // Registry with registered object that is then unregistered.

  let registry3 = new FinalizationRegistry(v => { holdings3.push(v); });

  let token3 = {}

  registry3.register({}, 1, token3);

  registry3.unregister(token3);

  // Registry with registered object that doesn't die.

  let registry4 = new FinalizationRegistry(v => { holdings4.push(v); });

  let object4 = {};

  registry4.register(object4, 1);

  // Registry observing cyclic JS data structure.

  let registry5 = new FinalizationRegistry(v => { holdings5.push(v); });

  registry5.register(makeJSCycle(4), 5);

  const { gc } = getJSTestingFunctions();

  gc();

  Promise.resolve().then(() => {

    checkNoCallbacks();

});

  postMessage('started');

function checkNoCallbacks() {

  is(holdings1.length, 0);

  is(holdings2.length, 0);

  is(holdings3.length, 0);

  is(holdings4.length, 0);

  is(holdings5.length, 0);

function checkResults() {

  is(holdings1.length, 0);

  let result = holdings2.sort((a, b) => a - b);

  is(result.length, 3);

  is(result[0], 1);

  is(result[1], 2);

  is(result[2], 3);

  is(holdings3.length, 0);

  is(holdings4.length, 0);

  is(holdings5.length, 1);

  is(holdings5[0], 5);

  postMessage('passed');

function is(a, b) {

  if (a !== b) {

    throw `Expected ${b} but got ${a}`;

function makeJSCycle(size) {

  let first = {};

  let current = first;

  for (let i = 0; i < size; i++) {

    current.next = {};

    current = current.next;

  current.next = first;

  return first;