The popular Jest JavaScript test framework will now flourish as a community-led project.

Meta is transferring its open source JavaScript testing framework, Jest, to the OpenJS Foundation. Jest is one of Meta’s top open source projects. It has become the “most used” tool for testing JavaScript projects, Meta says. It is particularly useful for testing projects built in React, another popular JavaScript library created at Facebook, which open-sourced it in 2013. 

Facebook introduced Jest as an open source project in 2014, but it was created in 2011 when Facebook’s chat feature was rewritten in JavaScript.

Rick Hanlon, a front end engineer on React core at Meta and Jest core contributor, commented on the gifting of Jest in a blog post. “With over 17 million weekly downloads and over 38,000 GitHub stars, Jest is the most used testing framework in the JavaScript ecosystem,” Hanlon writes. He adds that Jest is used by companies of all sizes, including Amazon, Google, Microsoft, and Stripe.

“We believe that transferring ownership of Jest to the community — and moving it into a foundation focused on supporting the JavaScript ecosystem — is an exciting and natural next step as Jest matures as an open source project.,” Hanlon says.

Hanlon adds, however, that “this move does not change how Jest is developed or released, and it does not directly affect developers using Jest to test their applications.”

The origin lies in Facebook’s Chat feature

Jest was created in 2011 when Facebook’s chat feature was rewritten in JavaScript. The increased complexity required a fast test-driven development cycle. It was open-sourced in 2014 and maintained part-time by engineers at Meta until 2016, when Christoph Nakazawa, a former Meta engineer and current Jest core contributor, overhauled the project with a dedicated team. During that time, engineers at Meta created many of the features users recognize Jest for today, including performance, watch mode, and snapshot testing, Hanlon explains.

“The OpenJS Foundation is committed to supporting the healthy growth of the JavaScript ecosystem and web technologies,” Hanlon continues. He adds that the Foundation does this by acting as “a neutral organization” to host and sustain projects and to collaboratively fund activities for the benefit of the community at large.

“Moving Jest to OpenJS will allow the Jest core team to lead the project moving forward,” he concludes.

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