React 15.5 Gets Ready For Rewrite
Written by Kay Ewbank   
Thursday, 13 April 2017

There's a new version of React with changes to make the transition to the next major version easier.  React is Facebook’s open source JavaScript library, which lets you describe what you want to render in a declarative way using shared components and elements.

The next release of React, version 16, will include a complete rewrite of React's internals along with other improvements to its usefulness. The rewrite has resulted in the need for the changes in React 15.5.

The first major change comes in the form of deprecation warnings when you use eact.PropTypes or React.createClass. The warnings are raised because the developers have extracted both React.PropTypes and React.createClass into their own packages. Both are still accessible via the main React object, but using either will log a one-time deprecation warning to the console when in development mode. This will enable future code size optimizations.

Writing about the new version, Andrew Clark, part of the Reactjs core team at Facebook,  says:

"Adding new warnings is not something we do lightly. Warnings in React are not mere suggestions — they are integral to our strategy of keeping as many people as possible on the latest version of React. We never add warnings without providing an incremental path forward.

So while the warnings may cause frustration in the short-term, we believe prodding developers to migrate their codebases now prevents greater frustration in the future."

The idea is that you should fix code that causes warnings in this version, and if your app produces no warnings in 15.5, it should continue to work in 16 without any changes.

The developers have provided a codemod to automatically change your code for each of the new deprecations.

Another change announced with React 15.5 is the cessation of active maintenance of React Addons packages. The developers say that in point of fact, most of the packages haven't been actively maintained in a long time, and they should continue to work indefinitely, but the developers recommend migrating away as soon as you can to prevent future breakages.


More Information

React On Facebook Code

React On Github

Related Articles

React 15 Released

Facebook's Relay For React Open Sourced

React 0.14 

Facebook Releases React Native


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