React Perf Tool

A Chrome DevTools extension to analyze the performance of your React app.

After reading React's 15.4 release notes, I learned that React already performance instrumentation using the window.performance API. This tool essentially provides a different view on the performance data already collected by React.

These are the types of questions that can be answered by this tool:

• Which components are taking the longest time on load?
  • Insight: Defer loading certain components (e.g. don't render content below the fold right away).
• What's taking the most time after certain user actions (e.g. scrolling a list-type view, clicking on a new route)?
  • Insight: Identify which components to write shouldComponentUpdate logic for.
• How many component instances are there at a given moment?
  • Insight: Unmount unused component instances

Note: This is a proof-of-concept and may have bugs.

Demo

Running it locally

1. Install modules: yarn / npm install (devDependency used for type checking)
2. Compile Typescript file: yarn ts
3. Go to chrome://extensions - click "Load unpacked extensions" - select react-perf-tool/extension
4. We'll use sound-redux a nice open-source SoundCloud client written in React.

• Clone my forked version of sound-redux (only recent versions of React have the performance instrumentation): git clone https://github.com/wwwillchen/sound-redux
• Install modules: yarn / npm install
• You'll need to modify one line in React so the performance measurements can be captured by the extension: In node_modules/react-dom/lib/ReactDebugTool.js: comment out the line: performance.clearMeasures(measurementName);
• Start the dev server for sound-redux: yarn start

5. Go to http://localhost:8080/?react_perf (you need the query param for React to measure performance timings)
6. Open Chrome DevTools and select the "React Perf" tab.