Cache busting with CRA React

As mentioned by some of the previous answers here, both the service worker and the (lack of) cache headers can conspire against you when it comes to seeing old versions of your React app.

The React docs state the following when it comes to caching:

Using Cache-Control: max-age=31536000 for your build/static assets, and Cache-Control: no-cache for everything else is a safe and effective starting point that ensures your user's browser will always check for an updated index.html file, and will cache all of the build/static files for one year. Note that you can use the one year expiration on build/static safely because the file contents hash is embedded into the filename.

As mentioned by @squarism, older versions of create-react-app defaulted to opt-out of service worker registration, while newer versions are opt-in. You can read more about that in the official docs. It's quite a straightforward process to match you configuration to the latest template if you started with an older version of create-react-app and you want to switch to the new behaviour.

Related questions:

• How to avoid caching for create-react-app
• ReactJS: How to prevent browser from caching static files?
• how to clear browser cache in reactjs

It appears that they changed from opt-out to opt-in with regards to the service worker. Here's the commit that changed the README and it has examples similar to Kerry G's answer:

https://github.com/facebook/create-react-app/commit/1b2813144b3b0e731d8f404a8169e6fa5916dde4#diff-4e6ec56f74ee42069aac401a4fe448ad

I had the same issue when I use create-react-app ( and deploy to heroku). It keeps showing the old version of my app 😡.

I found the problem seems to be on the browser side, it caches my old index.html with its outdated js bundle

You may want to add the following to your server side response header

"Cache-Control": "no-store, no-cache"

or if you are also using heroku create-react-app-buildpack, update the static.json file

"headers": { 
    "/**": { 
        "Cache-Control": "no-store, no-cache" 
    } 
}

I think in this way you can still keep that poor service worker 😂, and the latest content will be shown on the N+1 load (second refresh)

Hope this helps...

EDIT: create-react-app v2 now have the service worker disabled by default

This answer only apply for CRA v1

This is probably because of your web worker.

If you look into your index.js file you can see

registerServiceWorker();

Never wondered what it did? If we take a look at the file it got imported from we can see

// In production, we register a service worker to serve assets from local cache.

// This lets the app load faster on subsequent visits in production, and gives
// it offline capabilities. However, it also means that developers (and users)
// will only see deployed updates on the "N+1" visit to a page, since previously
// cached resources are updated in the background.

// To learn more about the benefits of this model, read {URL}
// This link also includes instructions on opting out of this behavior.

If you want to delete the web worker, don't just delete the line. Import unregister and call it in your file instead of the register.

import { unregister } from './registerServiceWorker';

and then call

unregister()

P.S. When you unregister, it will take at least one refresh to make it work