Deno improves JSX transform, WebAssembly support

Deno 1.16, the latest version of the JavaScript/TypeScript runtime, features support for a new JSX transform and WebAssembly reference types.

The newly supported JSX transform, which is featured in the React 17 JavaScript UI library, both improves the JSX transform API and allows automatic importing of the JSX runtime library. JSX is a syntax extension for JavaScript that is often used to describe what the UI should look like.

Deno 1.16 also adds an experimental API for listening to operating system signals. The new unstable API supersedes the existing Deno.signals API, which also was unstable. Other new features and improvements in Deno 1.16:

• WebAssembly reference types are supported, for using external references from JavaScript opaquely in WebAssembly modules.
• Since Deno 1.13, the Error.cause property has been supported as a way to attach a cause to an error. This is useful for debugging errors that happen deep inside of an application, so developers can wrap these errors in useful information to help debug issues. In Deno 1.16, the Error.cause property will be displayed in the console when an error is thrown or logged via a console.log. This matches the behavior of Node.js 17.
• fetch now supports fetching file URLs.
• Handshaking TLS connections now can be done explicitly.
• The Web Streams API now supports ReadableStreamBYOBReader and <a href="https://github.com/whatwg/streams/blob/main/writable-stream-abort-signal-explainer.md" rel="nofollow">signal</a> code.
• The Deno.startTlscode API, for writing an SMTP driver, is now stable.
• The per-test permissions feature introduced in Deno 1.10 is now stable.

Current users can upgrade to Deno 1.16 by running deno upgrade. Also, multiple methods are available for installing Deno for the first time. Deno 1.16 follows the October release of Deno 1.15.