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Deno Crate Organization
The document discusses the Deno runtime, its design principles, and how it differs from Node.js, emphasizing security, a modular structure using Rust crates, and built-in tooling like testing and formatting. Deno operates under a secure default model where access to files, network, or environment is strictly controlled, and it supports TypeScript natively. Key features include a single executable file, performance enhancements through native bindings, and compatibility with modern web browsers.
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Deno Crate Organization
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- 2. Craig Morten @CraigMorten • Howto publish Deno modules • How To Bundle Code For Deno Web Applications • Guide To Porting Node Modules To Deno • Countdown Of The Top Package Registries For Deno • What Is The Best Deno Web Framework? • Opine Tutorial Part 2: Creating A Website In Deno • Running Code From READMEs In 10 Lines Of Deno • Proxy Middleware For Deno • Testing Your Deno Apps With Mocha • GitHub Actions With Deno
- 3. an·a·gram /ˈanəˌɡram/ Noun • a word,phrase, or name formed by rearranging the letters of another, such as cinema, formed from iceman.
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- 5. “JavaScript has changedquite a bit in the last 10 years since I originally sat down to do Node.” -Ryan Dhal
- 6. 10 (8) ThingsRyan Regrets about Node • Not sticking with Promises • Security • The Build System: GYP • package.json • require("somemodule") is not specific • node_modules • require("module") without the extension “.js" • index.js
- 7. Node is fundamentallydivergent from the standardization of JavaScript since ES2015
- 8. Node has toomuch access to the computer it's running on
- 9. The module/package systemis a bit of a nightmare
- 10. "I imagine himstanding in the rain at night - stoically facing the dark battle that is software engineering.” -hashrock
- 11. Deno Principles Secure bydefault • No file, network, or environment access, unless explicitly enabled Supports TypeScript out of the box Ships only a single executable file Built-in utilities • Dependency inspector (deno info) and code formatter (deno fmt) Standard modules • Audited and guaranteed to work with Deno: deno.land/std
- 12. Origins • In 2015it was a project called V8 worker which was a binding to V8 and Go. • The idea was to disallow Go programmers from using V8's APIs to create random JS objects. • Instead they would be forced into a message passing system that would pass messages between Go and V8.
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- 14. Better separation ofconcerns inside the CLI • Sub-systems can be tested independently • Provides principled binding layer for CLI Many use cases for embedding a JS VM • Web servers customizable with JS (serverless) • Databases using JS for map-reduce • GUI applications like Electron
- 15. Rust Crates Unlike Node,a monolithic project, Deno is organized into a collection of Rust crates deno • Deno executable deno_typescript • Type-checking and type-stripping at compile-time deno_core • Ops and resources rusty_v8 • Rust interface to V8
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- 17. rusty_v8 V8 is aC++ library with 800,000 lines of code rusty_v8 is a framework for adding bindings to V8 • Zero cost Rust interface to V8 • Safe bindings to V8 • Ability to recompile V8 with different compilation settings
- 18. Zero cost Rustinterface to V8 • Objects manipulated in rusty_v8 are exactly the objects in C++ Safe bindings to V8 • The type system forces Local handles to be created in a HandleScope • Isolates are pegged to a thread for optimal usage Ability to recompile V8 with different compilation settings • Prebuilt binaries created through github actions are provided for most users • V8 source code is distributed inside a crate file. It does not depend on depot_tools
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- 20. deno_core Node Problems • Nocentralized binding interface in Node means no way to monitor metrics or perform security checks. • Many callbacks are issued from C++ without being requested from the JS side giving users the opportunity to create code without back pressure. Deno Solutions • Native bindings are done through “Ops”, native functions called from JS. • Everything in the executable is built on ops, which provides superior performance to Node.
- 21. Binary data • Parametersand return value are ArrayBuffers • ArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer Zero-copy • ArrayBuffers pass pointers back and forth between JS and Rust Integrated with event loop • An op either completes synchronously with a result or returns a promise corresponding to a Rust Future
- 22. Resources • Similar toa file descriptor in POSIX. • It is an integer identifier given to JS to reference some object allocated in Rust such as an open socket or file. • Resources are stored in the resource table and are removed from the table by Deno.close()
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- 25. Goals Only ship asingle executable (deno) Provide Secure Defaults • Unless specifically allowed, scripts can't access files, the environment, or the network Browser compatible • Subset of Deno programs which are written in JS and don’t use the global Deno namespace should run in a modern web browser without change Provide built-in tooling • Unit testing, code formatting, and linting to improve developer experience Does not leak V8 concepts into user land Be able to serve HTTP efficiently
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- 27. deno_typescript deno_core is JS-only •deno_typescript is where the TypeScript compiler is incorporated. • This is currently a work in progress and should not be used in production.