Hari 25: Web Workers & Concurrency

JavaScript adalah Single-Threaded

JavaScript berjalan pada satu thread (main thread). Operasi berat akan memblokir UI. Web Workers memungkinkan kode berjalan di thread terpisah.

// main.js
const worker = new Worker("worker.js");

worker.postMessage({ tipe: "hitung", data: 1000000 });

worker.onmessage = (event) => {
    console.log("Hasil:", event.data.hasil);
};

// worker.js
self.onmessage = (event) => {
    const { tipe, data } = event.data;
    if (tipe === "hitung") {
        let total = 0;
        for (let i = 1; i <= data; i++) total += i;
        self.postMessage({ hasil: total });
    }
};

Event Loop & Microtasks

console.log("1 - sync");

Promise.resolve().then(() => console.log("3 - microtask"));

setTimeout(() => console.log("4 - macrotask"), 0);

console.log("2 - sync");

// Output: 1, 2, 3, 4
// Urutan: sync → microtasks → macrotasks