The Secret Life of JavaScript: The Clone

How to use Web Workers to protect the Main Thread and prevent frozen UIs. Timothy clicked the "Export Report" button. On the screen, a small loading spinner appeared. But it wasn't spinning. It was frozen solid. Timothy tried to click another tab on the page, but the entire browser window was unresponsive. Ten seconds later, the UI suddenly unfroze, and the file downloaded. "It works," Timothy said, "but the application completely dies while it's processing the data." Margaret pulled up a chair. "You have built a beautiful kitchen, Timothy. But you only have one chef. If you ask him to chop ten thousand onions, he cannot also greet the customers." The Single Thread Margaret opened the performance tab and pointed to a massive, solid yellow block taking up the timeline. "JavaScript is single-threaded," Margaret explained. "We call it the Main Thread, but you should think of it as the UI Thread. Its primary job is to paint the screen, run animations, and listen for clicks." Timothy pointe