How to initialize Sentry only once in a web application?

[anaamnizami]

Hi everyone,
I've integrated Sentry into my web application following the documentation, but I've noticed that the initialization function is called every time I refresh the page. While this makes sense, I'm wondering if there's a way to ensure that Sentry is initialized only once, rather than on every page refresh.
Is this behavior typical for Sentry integrations, or are there best practices or methods to ensure that Sentry is initialized only once in a web application?
Any guidance or suggestions would be greatly appreciated. Thanks in advance!

https://docs.sentry.io/platforms/javascript/guides/react/

[lforst]

If by refreshing the page you mean for example reloading it, then yes, the SDK being initialized every time is expected and best practice. In fact, if you are using React, React itself also initializes every time you refresh the page.

[egolessengineer]

Understanding the concern behind wanting to initialize Sentry only once, it's important to clarify what "initializing only once" means in the context of web applications:

1. Per Page Load Initialization: In traditional multi-page applications (MPAs), where each navigation leads to a full page refresh, scripts (including Sentry) are loaded anew with each page. This is expected behavior, as the global JavaScript context is reset, and all scripts are re-executed.

2. Single Initialization in SPAs: In SPAs, where navigation does not trigger a full page reload, scripts are typically loaded and initialized just once when the application starts. Sentry included should behave this way in an SPA, initializing once when the application loads and remaining active through subsequent "virtual" page navigations handled by your frontend router.

👇 Try this:

Placement of Initialization Code: Ensure that the Sentry initialization code is placed in a part of your application that is executed only once during the app's lifetime. In React, for example, this might be at the root component or inside a useEffect hook with an empty dependency array in your app's entry point file.
Conditional Initialization: If there's a specific reason to suspect Sentry is re-initializing (though typically it should not if placed correctly), you could implement a simple check to ensure the initialization code runs only if Sentry is not already initialized. However, this is more of a workaround than a best practice, as the proper placement should suffice.

if (!window.Sentry) {
  Sentry.init({
    // Your Sentry configuration
  });
}

Review Build and Deployment Process: In rare cases, the build process or dynamic module loading might cause unexpected behavior. Ensure your build process or module loader isn't inadvertently re-executing initialization logic.