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emotion-js/emotion

★ 18,011JavaScriptAudience · developerComplexity · 2/5ActiveLicenseSetup · easy

TLDR

Write CSS styles directly in JavaScript code alongside your components, keeping styling logic together and using JavaScript variables in your styles.

Mindmap

mindmap
  root((emotion))
    What it does
      CSS in JavaScript
      Style components together
      Use JS variables
    Key features
      Performance caching
      Predictable specificity
      Source maps
    How to use
      Standalone package
      React integration
      Babel plugin
    Tech stack
      JavaScript
      TypeScript
      React optional

Things people build with this

USE CASE 1

Build a React component library where each component's styles are defined in the same file as its logic.

USE CASE 2

Create dynamic styles that change based on user input or application state without writing separate CSS files.

USE CASE 3

Set up a design system where style variables and theme colors are shared across all components via JavaScript.

USE CASE 4

Debug styling issues faster with source maps and meaningful class names that show which component created each style.

Tech stack

JavaScriptTypeScriptReactBabel

Getting it running

Difficulty · easy Time to first run · 5min
Use freely for any purpose, including commercial use, as long as you keep the copyright notice.

In plain English

Emotion is a JavaScript library for writing CSS styles directly inside JavaScript or TypeScript code, a technique called CSS-in-JS. Normally, CSS (the language that controls how web pages look) lives in separate files. Emotion lets you define styles as JavaScript objects or strings right next to the component code they apply to, which makes it easier to keep styles and logic together and to use JavaScript variables and logic inside your styles. Emotion is designed with performance in mind and uses heavy caching in production environments to keep things fast. It handles the tricky problem of CSS specificity, the rules that determine which style wins when multiple rules apply to the same element, in a predictable way, avoiding a common source of bugs. It also generates source maps and meaningful label names in development mode to make debugging easier. The library works as a standalone package for plain JavaScript, and has a dedicated integration for React that enables a special css prop you can add directly to any element. An optional Babel plugin (a code-transformation tool that runs during your build step) enables additional optimizations. Emotion is open source and licensed under the MIT license.

Copy-paste prompts

Prompt 1
Show me how to set up Emotion in a React project and write a styled button component using the css prop.
Prompt 2
How do I use Emotion to create a theme system where I can switch between light and dark modes dynamically?
Prompt 3
What's the difference between using Emotion's css function versus the styled component API, and when should I use each?
Prompt 4
Help me migrate an existing CSS file to Emotion by converting the styles to JavaScript objects in my React component.
Prompt 5
How do I configure the Babel plugin for Emotion to get better performance and debugging in production?
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Generated 2026-05-18 · Model: sonnet-4-6 · Verify against the repo before relying on details.