Demystifying the Browser Render Cycle: useLayoutEffect, requestAnimationFrame, and Layout Thrashing
The article explains the browser's render cycle and how React developers can optimize performance by understanding timing mechanisms like useLayoutEffect and requestAnimationFrame. It details the sequence of events in a browser frame, including JavaScript execution, layout, paint, and composite stages. The article also warns against layout thrashing and emphasizes proper use of APIs to achieve smooth UI updates.
- ▪The browser has 16.6 milliseconds to complete a frame on a 60Hz display, following a strict rendering pipeline.
- ▪React's useLayoutEffect runs synchronously after DOM mutations but before the browser's layout and paint steps.
- ▪requestAnimationFrame executes right before the browser recalculates styles and layout, making it ideal for animations.
- ▪Running excessive DOM reads and writes in the wrong order can lead to layout thrashing, degrading performance.
- ▪useEffect runs after painting, making it non-blocking and suitable for side effects that don't impact layout.
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try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 1597891) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Kapil Thukral Posted on May 17 Demystifying the Browser Render Cycle: useLayoutEffect, requestAnimationFrame, and Layout Thrashing #react #performance #webdev #javascript As React developers, we often live in a comfortable world of state, props, and virtual DOMs. React handles the heavy lifting of updating the UI, and we rarely have to think about how pixels actually hit the glass.
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