deno2node

deno2node

Transpiles Deno projects into .js and .d.ts for Node.js.

Uses ts-morph to rewrite imports, typecheck, and emit.

Motivation

Writing libraries Deno-first makes it easy to publish to https://deno.land/x, and simplifies development experience:

Deno [...] requires no explicit transpilation step, and ships with 0conf tooling that works well together.

CLI Usage

$ deno run \
  --no-check \
  --unstable  \
  --allow-read \
  --allow-write  \
  https://deno.land/x/deno2node/src/cli.ts \
  <tsConfigFilePath>

As a by-product of end-to-end testing, Node.js build is also available:

$ npm install --save-dev --save-prefix='~' deno2node

$ deno2node <tsConfigFilePath>

tsconfig.json is used to specify compilerOptions and source files to include.

API reference explains transformations and configuration.

Note: output and diagnostics will change across minor versions.

Shimming

To use Deno globals not available in Node.js, create and register a file exporting all the shims you need:

// @filename: src/shim.node.ts
export * from "deno.ns";
export * from "node-fetch";
export { default as fetch } from "node-fetch";

// @filename: tsconfig.json
{
  "deno2node": {
    "shim": "src/shim.node.ts" // path to shim file, relative to tsconfig
  }
}

Runtime-specific code

When the provided transformations are not enough, you can provide a Node-specific (<anything>.node.ts) and a Deno-specific (<anything>.deno.ts) version of any file.

deno2node will ignore the Deno version and rewrite imports to use the Node.js version instead.

This technique has many uses. deno2node uses it to import from https://deno.land/x. grammy will probably also use it to abstract away platform-specific APIs.

Vendoring

If you import a module which has no npm equivalent, deno2node will vendor it in vendorDir, if specified:

// @filename: tsconfig.json
{
  "deno2node": {
    "vendorDir": "src/.deno2node/vendor/" // path within `rootDir`
  }
}

Vendoring requires --allow-env, to locate Deno cache.

Note: vendoring is currently slow and poorly tested.