How Browsers Render Websites (The Step-by-Step Process)
When you type a URL, the browser does an insane amount of work in milliseconds. This video breaks down the "Critical Rendering Path" (CRP)—the exact steps a browser takes to turn your HTML, CSS, and JavaScript into pixels on the screen.
Understanding this process is the key to fixing slow websites and mastering frontend performance.
📘 Topics Covered:
0:00 Intro: The Browser's Dilemma
0:49 What is Progressive Rendering?
1:39 The Critical Rendering Path (CRP)
2:18 Step 1: Building the DOM Tree (HTML Parsing)
2:58 Step 2: Building the CSSOM Tree (Styles)
3:40 Step 3: JavaScript & Parser Blocking
4:25 Step 4: The 'defer' Attribute Solution
5:13 Step 5: The Render Tree
5:43 Step 6: Layout (Reflow)
6:15 Step 7: Paint & Compositing
📚 Resources & Further Reading:
MDN Web Docs - Populating the Page:
https://developer.mozilla.org/en-US/d...
Google Developers - Critical Rendering Path:
https://web.dev/learn/performance/und...
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