Here at Sentry, we like to dogfood our product as much as possible. Sometimes, it results in unusual applications of our product and sometimes these unusual applications pay off in a meaningful way. In this blog post, we’ll examine one such case where we use the Sentry JavaScript SDK to instrument Jest (which runs our frontend test suite) and how we addressed the issues that we found.

Transactions are sent when your service receives a request and sends a response, like an API call or a page load. Within each transaction is a series of operations. We built Operations Breakdown to help you, the developer, quickly see how much time was spent in each operation within a transaction. Why? Simple, so you can address the operations with the longest duration and likely causing annoying performance issues for your customer.