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Web Performance Optimization & Lighthouse · Lesson

CSS-in-JS Performance Impact

Analyze the performance implications of different CSS-in-JS solutions and best practices for their use.

What is CSS-in-JS?

CSS-in-JS is a technique where CSS is authored directly within JavaScript code. Instead of separate .css files, your styles live alongside your components.

It offers benefits like component-scoped styles, dynamic styling based on props, and easier management of component-specific CSS.

How CSS-in-JS Works

Typically, CSS-in-JS libraries convert your JavaScript style definitions into actual CSS rules. These rules are then injected into the HTML <head> as <style> tags at runtime.

Alternatively, some advanced solutions can extract the CSS into static .css files during the build process.

All lessons in this course

  1. Critical CSS and CSS Delivery
  2. Optimizing Font Loading
  3. CSS-in-JS Performance Impact
  4. Reducing Unused CSS
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