Deno is a secure runtime environment for executing JavaScript and TypeScript code. It was created by Ryan Dahl, the original creator of Node.js, with the aim of addressing some of the limitations and security concerns associated with Node.js.
Deno provides a runtime for running JavaScript and TypeScript code outside of a web browser environment. It offers a secure and sandboxed execution environment by default, meaning that the code executed within Deno is isolated from the underlying operating system and has limited access to system resources. This security model helps prevent unauthorized access or malicious actions.
Some key features of Deno include:
- Security: Deno emphasizes security as a core principle. By default, Deno runs in a secure mode where scripts have restricted access to the file system, network, and other potentially sensitive operations. Access to specific resources or permissions must be explicitly granted to scripts using command-line flags or programmatic permissions.
- TypeScript Support: Deno natively supports TypeScript, a typed superset of JavaScript. It allows developers to write and execute code in TypeScript without the need for additional build steps or configurations. TypeScript brings static typing and other advanced language features to JavaScript, improving code quality and maintainability.
- Module System: Deno utilizes a module system that conforms to the ECMAScript modules specification. It supports importing modules using standard import statements and can load modules from local files or remote URLs. Deno also provides a built-in package manager called “Deno Registry” for discovering and fetching dependencies.
- Built-in Tools: Deno ships with several built-in tools that simplify common development tasks. It includes a bundled TypeScript compiler, a file watcher for automatic reloads, and a built-in test runner for executing unit tests. These tools enhance developer productivity by eliminating the need for external dependencies or configuration.
- Standard Library: Deno includes a standard library with a set of utility modules for common tasks such as file I/O, HTTP requests, and cryptography. The standard library aims to provide a consistent and reliable set of modules that developers can rely on without external dependencies.
Deno has gained popularity for its focus on security, developer experience, and modern JavaScript/TypeScript features. It provides an alternative runtime environment for running JavaScript and TypeScript applications outside of the browser, addressing some of the concerns associated with traditional server-side JavaScript execution.
deno Command Examples
1. Run a JavaScript or TypeScript file:
# deno run /path/to/file.ts
2. Start a REPL (interactive shell):
# deno
3. Run a file with network access enabled:
# deno run --allow-net /path/to/file.ts
4. Run a file from a URL:
# deno run https://deno.land/std/examples/welcome.ts
5. Install an executable script from a URL:
# deno install https://deno.land/std/examples/colors.ts