TypeScript setup

esrun does not execute TypeScript, nor does it inject ambient globals like Bun or process. esdev runs TypeScript directly — types erased, never checked — and the definitions below are what your editor and tsc --noEmit use.

One-command setup

Shell

esdev --install-types

It adds @opentf/esrun-types as a dev dependency, using the package manager your lockfile names (bun, pnpm, yarn, npm), and adds it to compilerOptions.types — creating a tsconfig.json if you don't have one, or merging into an existing one without touching your other settings.

What it configures

JSON

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "types": ["@opentf/esrun-types"]
  },
  "include": ["**/*.ts"]
}

types is what editors and language servers load globally, so the runtime:* modules resolve everywhere, not just per-file.

Leave `lib` unset

With no lib, TypeScript uses the default for your target — lib.esnext.full for ESNext — which already includes the web APIs this runtime provides: fetch, URL, crypto, the streams, TextEncoder, and Temporal from TypeScript 7. Setting lib explicitly replaces that default, so a config naming only ["ESNext"] loses all of them.

By hand

Shell

npm install --save-dev @opentf/esrun-types

Then add "types": ["@opentf/esrun-types"] to compilerOptions, or put /// <reference types="@opentf/esrun-types" /> in one file.

Use it

Your editor now provides intellisense, inline docs, and type checking for every built-in module:

TypeScript

import { file } from "runtime:fs";

// Your IDE knows `text()` returns a Promise<string>
const data = await file("./config.json").text();