How does dnt compare to manually converting Deno code to Node?

dnt automates the entire process, including module rewriting, shim injection, and testing, whereas manual conversion requires extensive effort to handle Deno APIs and dependencies. It reduces errors and ensures consistency, but adds tooling complexity.

How to handle Deno.test in Node with dnt?

dnt automatically runs Deno.test suites in Node.js after transformation by default. You can configure test-specific shims using the 'shims' option with 'dev' settings, and adjust test file matching with testPattern and rootTestDir.

Can dnt handle custom Deno APIs not covered by built-in shims?

Yes, dnt supports custom shims where you can specify local or remote modules to shim globals, as described in the 'Custom Shims' section. This allows flexibility but requires manual implementation and testing.

What are the limitations with CommonJS output in dnt?

dnt errors if code uses top-level await when outputting CommonJS, requiring code restructuring or disabling CommonJS output via scriptModule: false. Also, some shims may not work optimally in older Node versions.

How to publish a Deno CLI tool to npm using dnt?

Use a 'kind: "bin"' entry point in the build configuration, which adds a bin entry to package.json and a shebang to the output. Then, run the build script and publish from the npm directory, as outlined in the setup steps.

Does dnt support TypeScript configurations from deno.json?

Yes, starting from version 0.42, dnt auto-discovers deno.json configs, and you can explicitly specify one using the configFile option, ensuring alignment with your Deno project settings.

Open-Awesome

dnt

MITRust0.42.3

A build tool that transforms Deno modules into npm packages for Node.js, handling module specifiers, shims, and testing.

GitHub

1.3k stars48 forks0 contributors

What is dnt?

dnt (Deno to Node Transform) is a build tool that converts Deno modules into npm packages compatible with Node.js. It rewrites module specifiers, injects shims for Deno APIs, generates ESM and CommonJS outputs, and runs tests in Node.js, solving the problem of publishing Deno code to the npm registry.

Target Audience

Deno developers who want to distribute their libraries as npm packages for use in Node.js projects, or teams maintaining dual Deno/Node.js codebases.

Value Proposition

Developers choose dnt because it automates the entire Deno-to-Node conversion process with robust shimming, type checking, and testing, reducing manual effort and ensuring compatibility. Its flexibility in handling custom shims, specifier mappings, and multiple entry points makes it the most comprehensive tool for this niche.

Overview

Deno to npm package build tool.

Use Cases

Best For

Publishing Deno libraries to npm for Node.js users
Maintaining a single codebase that targets both Deno and Node.js
Automating CI/CD pipelines for Deno-to-npm package builds
Converting Deno CLI tools into npm-executable binaries
Handling Deno-specific APIs like the Deno namespace in Node.js
Generating dual ESM and CommonJS outputs from Deno modules

Not Ideal For

Projects that don't use Deno at all and are purely Node.js-based
Teams seeking a zero-configuration, drop-in build tool without any setup
Codebases heavily reliant on top-level await that must output CommonJS
Targeting Node.js v14 or older where shim compatibility is limited and requires workarounds

Pros & Cons

Pros

Automated Module Rewriting

Transforms Deno import URLs to Node.js-compatible specifiers, including esm.sh and remote modules, handling a complex manual process automatically.

Comprehensive API Shimming

Injects shims for the Deno namespace and other globals using packages like @deno/shim-deno, enabling Deno code to run in Node.js with minimal code changes.

Dual Module Output

Generates both ESM and CommonJS/UMD packages alongside TypeScript declaration files by default, ensuring broad compatibility across Node.js environments.

Integrated Testing Pipeline

Runs Deno.test suites in Node.js after transformation, verifying functionality and catching issues before publishing, as shown in the build logs.

Cons

Complex Configuration Overhead

Setting up custom shims, specifier mappings, and handling edge cases like top-level await requires manual intervention and deep familiarity with the tool's options.

Limited Old Node Support

The README admits that targeting Node v14 and below is problematic, with certain shims not working reliably and necessitating workarounds like Deno.test-only shimming.

Build Time and Shim Overhead

The transformation process adds build time, and injected shims can increase package size and runtime overhead, which may impact performance-sensitive applications.

Frequently Asked Questions

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