processTicksAndRejections.js

function processTicksAndRejections() {
  let tock;
  do {
    while (tock = queue.shift()) {
     ...

      try {
        const callback = tock.callback;
        if (tock.args === undefined) {
          callback();
        } else {
          const args = tock.args;
          switch (args.length) {
            case 1: callback(args[0]); break;
            case 2: callback(args[0], args[1]); break;
            ...
            default: callback(...args);
          }
        }
      } finally {
        ...
      }

      ...
    }
    runMicrotasks();
  } while (!queue.isEmpty() || processPromiseRejections());
  ...
}