mediumFrontend EngineerData Visualization
What are Web Workers and how do they enable parallel processing in the browser?
Posted 18/04/2026
by Mehedy Hasan Ador
Question Details
At a data visualization company: "Our chart rendering blocks the main thread for 2 seconds on 100K data points. Users can't interact during that time."
Suggested Solution
Web Workers run in separate threads
// main.js
const worker = new Worker("chart-worker.js");
worker.postMessage({ type: "render", data: largeDataset });
worker.onmessage = (e) => { document.getElementById("chart").innerHTML = e.data.chartSVG; };
// chart-worker.js — doesn't block UI!
self.onmessage = (e) => {
const result = heavyChartComputation(e.data.data);
self.postMessage({ chartSVG: result });
};
Main thread stays interactive while worker processes data. Small overhead (~50ms to start worker).