1.6.1 • Public • Published

🧙‍♂️ bundle-wizard

npm version

This command line utility makes it simple to create visualizations of the JS bundles that were fetched for any specific page (or "entry point") of a web app.


npx bundle-wizard reddit.com

bundle-wizard interaction showing code for reddit

Check out a live demo of this visualization

Try it out on a production app:

Try any of the following commands to take a peek at the JavaScript code different sites are shipping:

  1. npx bundle-wizard reddit.com
  2. npx bundle-wizard codesandbox.io
  3. npx bundle-wizard gatsbyjs.org
  4. npx bundle-wizard codecademy.com
  5. npx bundle-wizard id.atlassian.com

Try it out on an app running locally:

Want to use bundle-wizard but haven't deployed your app yet? It's as easy as:

1. Build your app locally

e.g. npm run build

2. Serve the build folder

e.g. npx serve -s build

3. Call bundle-wizard with the correct localhost url

e.g. npx bundle-wizard localhost:5000/sign-up

Additional features

View source code

If sourcemaps are properly configured you should be able to click on a square to see the code it represents:

demonstration of code feature

(Note: for performance reasons, this functionality will be automatically stripped if you decide to package your bundle-wizard files in order to host or share them).

Filter bundles with regex

Want to know all the bundles that contain code from certain library (say, momentjs or lodash)? Wondering how much weight in your bundles is from node_modules vs custom code? You can answer questions like these by putting a search string or regex into the bottom search bar that allows you to filter the view based on the name of the containing folder bundle name, or script:

demo of simple search

Optional command line arguments

url (initial argument)

To skip the initial prompt, provide a url as a first argument:

npx bundle-wizard reddit.com

interact flag

If you need to do some work in the browser getting the page ready for analysis (perhaps by signing in and then visiting a certain page), use the following command:

npx -p puppeteer -p bundle-wizard bundle-wizard --interact

The persistent npm equivalent would be running:

npm install -g puppeteer bundle-wizard

bundle-wizard --interact

You might be wondering why you have to install puppeteer as a peer dependency to use the interact command. By default bundle-wizard uses puppeteer-core, which is faster to download than puppeteer because it doesn't come bundled with a version of chromium. Since the --interact command opens a browser in non-headless mode, unlike the default bundle-wizard command, it requires the full puppeteer package to work reliably.

After running this command and specifying a url, you will see a browser window that will pop up that you can interact with. When you are ready to proceed, type y into the console in respond to the waiting prompt to reload the page and start measuring performance.

Note: While this tool does not record any data, it's still recommended from a common sense perspective to enter login information only for test accounts.

desktop flag

By default, bundle-wizard will analyze a mobile version of the site. To analyze the desktop version instead, pass the --desktop flag:

npx bundle-wizard --desktop

ignoreHTTPSErrors flag

If you are running an HTTPS connection on localhost and want to test a local site, you'll need to use this setting to prevent self-signed certificate errors:

npx bundle-wizard https://localhost:5000 --ignoreHTTPSErrors

port argument

By default, bundle-wizard will try to find an open port in the 3000 range. However, if you'd like it to run on a certain port, you can do so by passing in a value for --port:

npx bundle-wizard https://localhost:3000 --port=4000

How it works

bundle-wizard uses Puppeteer to download a web page, measure performance, and examine the JavaScript it sends to the client. It then analyzes the code using the awesome source-map-explorer library and creates a custom visualization.

Requirement: downloadable sourcemaps

This utility downloads sourcemaps from the url you provide. This requires the sourcemaps to be publically available, or at least available on your network. You might need to point to a testing instead of production build, for instance, as some apps disable sourcemaps in production.

Don't have access to sourcemaps in your prod app? Try building your app locally.

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  • aholachek