const messagesReceived = new Set(); for (let i = 0; i < 4; i++) { const worker = new Worker( new URL("./workers/message_before_close.js", import.meta.url).href, { type: "module", name: String(i) }, ); worker.addEventListener("message", () => { messagesReceived.add(i); if (messagesReceived.size == 4) { console.log("received all 4 responses from the workers"); } }); worker.postMessage({}); } globalThis.addEventListener("unload", () => { if (messagesReceived.size !== 4) { console.log( "received only %d responses from the workers", messagesReceived.size, ); } }); export {};