Deno 2.0, the next major version of the Deno runtime, has reached the release candidate stage, bringing significant updates and improvements. This JavaScript, TypeScript, and WebAssembly runtime, known for being a modern alternative to Node.js, introduces notable changes in global variables, dependency management, and permissions. Developers eager to explore these new features can access the release candidate by running deno upgrade followed by deno upgrade rc in their terminal.
One of the most impactful changes in Deno 2.0 is the handling of global variables. The window global, originally introduced in Deno 1.0 for better browser compatibility, has now been removed. While this decision may initially seem restrictive, it addresses long-standing issues that caused unexpected bugs in various libraries. In contrast, Deno 2.0 introduces the process global, a feature long requested by developers. This addition enhances compatibility with existing Node.js code, making it easier for projects to transition between the two runtimes.
Despite adding the process global, DenoLand—the organization behind Deno—still emphasizes the importance of explicit imports. To guide developers toward best practices, a new no-process-global lint rule has been introduced. This rule provides suggestions and quick fixes directly within the editor, ensuring that code remains structured and maintainable. While the inclusion of process makes Deno more flexible, developers are encouraged to use import statements wherever possible.
Beyond global variables, Deno 2.0 also brings improvements in dependency management and security permissions. These refinements aim to streamline the developer experience while maintaining the runtime’s core principles of security and efficiency. As the final release approaches, developers can expect a runtime that not only boosts compatibility with existing JavaScript ecosystems but also strengthens Deno’s position as a powerful alternative to Node.js.