Express 5 is finally out

Express 5 has finally arrived after years of development, marking a significant evolution for one of the most popular Node.js frameworks! The update brings several new features, enhancements, and some breaking changes, making it both exciting and necessary to review before migrating.
Key Highlights of Express 5:

Modern Node.js Support:
Express 5 now requires Node.js 18 or higher, dropping support for older Node versions. This decision enables the framework to leverage the latest language and performance improvements from Node.js, aligning it with modern standards.

Promise Handling in Middleware:
Error handling is more robust with native Promise support. Now, rejected promises in asynchronous middleware will be automatically forwarded to the error-handling middleware, preventing server crashes caused by unhandled errors.

Route Matching Overhaul:
Path matching has become more precise with new syntax. Previously common patterns using regular expressions (like /:foo(\\d+)) are no longer supported, mitigating potential security vulnerabilities such as ReDoS (Regular Expression Denial of Service) attacks. Additionally, the route parameters are now more explicit, requiring all variables to be named for clarity.

The Return of app.router:
The app.router object, removed in Express 4, is back in Express 5, bringing enhanced routing capabilities.

Body Parsing Changes:
Body parsing functionality has been tweaked, allowing more customization when handling URL-encoded data, which improves security and prevents nested JSON abuse.

Not Yet the Default Release:
Even though Express 5 is ready, it’s currently tagged as next on npm, not the default latest. This is partly due to ongoing efforts to update documentation and dependencies like TypeScript’s DefinitelyTyped ecosystem, and the project is also appealing for more contributors to help.

The release of Express 5 is a significant milestone not just for the framework but for its ecosystem. However, with breaking changes and dependency updates, developers will need to carefully plan their migration strategies. While the framework remains lightweight and performant, the developers have positioned this release as the foundation for future growth.

This long-awaited release also reflects the open-source community’s challenges, as it took years to finalize the update without heavyweight corporate sponsorship, unlike competitors like React or Angular. You can try the new version by installing it from npm with npm install express@next for now.

For detailed migration guidance and more nuanced technical aspects, check out the official Express.js documentation and the relevant community discussions.

To Know More - https://github.com/expressjs/express/blob/5.0/History.md