I found an import from “bippy” in react-scan source code. I wanted to find out what this is about. In this article, you will understand the below concepts

What is react-scan?
What is Bippy?
How did I find this package?

What is react-scan?

react-scan helps you scan for React performance issues and eliminate slow renders in your app.

Installation

You can run the below command to install react-scan


npm i react-scan

Usage

react-scan provides usage documentation.

What is Bippy?

I copied the below description from Bippy’s readme.

bippy is a toolkit to hack into react internals

by default, you cannot access react internals. bippy bypasses this by “pretending” to be react devtools, giving you access to the fiber tree and other internals.

works outside of react — no react code modification needed
utility functions that work across modern react (v17–19)
no prior react source code knowledge required


import { onCommitFiberRoot, traverseFiber } from 'bippy';
 
onCommitFiberRoot((root) => {
  traverseFiber(root.current, (fiber) => {
    // prints every fiber in the current React tree
    console.log('fiber:', fiber);
  });
});

[!WARNING] ⚠️⚠️⚠️ this project may break production apps and cause unexpected behavior ⚠️⚠️⚠️

this project uses react internals, which can change at any time. it is not recommended to depend on internals unless you really, really have to. by proceeding, you acknowledge the risk of breaking your own code or apps that use your code.

bippy allows you to access and use react fibers outside of react components.

a react fiber is a “unit of execution.” this means react will do something based on the data in a fiber. each fiber either represents a composite (function/class component) or a host (dom element)

fibers are useful because they contain information about the react app (component props, state, contexts, etc.). a simplified version of a fiber looks roughly like this:


interface Fiber {
  // component type (function/class)
  type: any;
 
  child: Fiber | null;
  sibling: Fiber | null;
 
  // stateNode is the host fiber (e.g. DOM element)
  stateNode: Node | null;
 
  // parent fiber
  return: Fiber | null;
 
  // the previous or current version of the fiber
  alternate: Fiber | null;
 
  // saved props input
  memoizedProps: any;
 
  // state (useState, useReducer, useSES, etc.)
  memoizedState: any;
 
  // contexts (useContext)
  dependencies: Dependencies | null;
 
  // effects (useEffect, useLayoutEffect, etc.)
  updateQueue: any;
}

Now that we understand the basics, let me tell you how I ended up finding this bippy package.

How did I find Bippy?

react-scan has the below packages folder.

scan/src/index.ts

scan is where I should be looking to understand react-scan internal source code. This below code is picked from packages/scan/src/index.ts.


import { init } from './install-hook'; // Initialize RDT hook
 
init();
 
export * from './core/index';

init is imported from another file, install-hook.ts

install-hook.ts


import { installRDTHook } from 'bippy';
 
// Initialize React DevTools hook
const init = () => {
  installRDTHook();
};
 
init();
 
export { init };

The above code is picked from install-hook.ts. Now init calls another function installRDTHook() that is imported from ‘bippy’. This is where I have found bippy and wanted to find out more about this package.

Bippy is written by the same author, Aiden Bai, who also wrote react-scan.

installRDTHook

There is no mention of installRDT in the react-scan documentation

And yet it is found to be used in install-hook.ts as shown below


import { installRDTHook } from 'bippy';
 
// Initialize React DevTools hook
const init = () => {
  installRDTHook();
};
 
init();
 
export { init };

About me:

Hey, my name is Ramu Narasinga. I study large open-source projects and create content about their codebase architecture and best practices, sharing it through articles, videos.

I am open to work on interesting projects. Send me an email at ramu.narasinga@gmail.com

My Github — https://github.com/ramu-narasinga

My website — https://ramunarasinga.com

My Youtube channel — https://www.youtube.com/@thinkthroo

Learning platform — https://thinkthroo.com

Codebase Architecture — https://app.thinkthroo.com/architecture

Best practices — https://app.thinkthroo.com/best-practices

Production-grade projects — https://app.thinkthroo.com/production-grade-projects