invariant is a small but crucial package for enforcing runtime invariants. It throws an error if a condition is not met, providing a standardized and informative error message. Often used in libraries and frameworks, like React, to ensure internal consistency and prevent unexpected behavior. This helps developers catch errors early and understand the root cause, leading to more robust and predictable software. It promotes defensive programming practices and simplifies debugging.
The npm package invariant was actively released between September 2014 and March 2018, with occasional releases. The initial versions (1.x) were released in September 2014. Version 2 saw several releases between February 2015 and March 2018. Since March 2018, there have been no new releases.
Invariant's npm package downloads saw steady growth from March 2024 (41.8M) to July 2025 (101.6M). Downloads remained high until August 2025 (78.8M). September 2025 data (30.1M) is incomplete, showing a sharp, likely inaccurate, decline in downloads.
