jiti

Just-in-Time Typescript and ESM support for Node.js.

Important

This is the development branch for jiti v2. Check out jiti/v1 for latest stable docs and unjs/jiti#174 for the v2 roadmap.

✅ Features

• Seamless Typescript and ESM syntax support
• Seamless interoperability between ESM and CommonJS
• Synchronous API to replace require()
• Asynchronous API to replace import()
• ESM Loader support
• Super slim and zero dependency
• Smart syntax detection to avoid extra transforms
• Node.js native require cache integration
• Filesystem transpile with hard disk caches
• Custom resolve aliases

🌟 Used by

• Docusaurus
• FormKit
• Histoire
• Knip
• Nitro
• Nuxt
• PostCSS loader
• Rsbuild
• Size Limit
• Slidev
• Tailwindcss
• Tokenami
• UnoCSS
• WXT
• Winglang
• Graphql code generator
• Lingui
• Scaffdog
• ...UnJS ecosystem
• ...58M+ npm monthly downloads
• ...5.5M+ public repositories
• [ pr welcome add yours ]

💡 Usage

CLI

You can use jiti CLI to quickly run any script with Typescript and native ESM support!

npx jiti ./index.ts

# or

jiti ./index.ts

Programmatic

// --- Initialize ---

// ESM
import { createJiti } from "jiti";
const jiti = createJiti(import.meta.url);

// CommonJS
const { createJiti } = require("jiti");
const jiti = createJiti(__filename);

// --- ESM Compatible APIs ---

// jiti.import() acts like import() with Typescript support
await jiti.import("./path/to/file.ts");

// jiti.esmResolve() acts like import.meta.resolve() with additional features
const resolvedPath = jiti.esmResolve("./src");

// --- CJS Compatible APIs ---

// jiti() acts like require() with Typescript and (non async) ESM support
jiti("./path/to/file.ts");

// jiti.resolve() acts like require.resolve() with additional features
const resolvedPath = jiti.resolve("./src");

You can also pass options as second argument:

const jiti = createJiti(import.meta.url, { debug: true });

Register global ESM loader

You can globally register jiti using global hooks.

Note: This is an experimental approach and only tested to work on Node.js > 20. I don't recommend it and unless you have to, please prefer explicit method.

import "jiti/register";

Or:

node --import jiti/register index.ts

⚙️ Options

debug

• Type: Boolean
• Default: false
• Environment variable: JITI_DEBUG

Enable verbose logging. You can use JITI_DEBUG=1 <your command> to enable it.

fsCache

• Type: Boolean | String
• Default: true
• Environment variable: JITI_FS_CACHE

Filesystem source cache (enabled by default)

By default (when is true), jiti uses node_modules/.cache/jiti (if exists) or {TMP_DIR}/jiti.

Note: It is recommended to keep this option enabled for better performance.

moduleCache

• Type: String
• Default: true
• Environment variable: JITI_MODULE_CACHE

Runtime module cache (enabled by default).

Disabling allows editing code and importing same module multiple times.

When enabled, jiti integrates with Node.js native CommonJS cache store.

transform

• Type: Function
• Default: Babel (lazy loaded)

Transform function. See src/babel for more details

sourceMaps

• Type: Boolean
• Default false
• Environment variable: JITI_SOURCE_MAPS

Add inline source map to transformed source for better debugging.

interopDefault

• Type: Boolean
• Default: false
• Environment variable: JITI_INTEROP_DEFAULT

Return the .default export of a module at the top-level.

alias

• Type: Object
• Default: -
• Environment variable: JITI_ALIAS

Custom alias map used to resolve ids.

nativeModules

• Type: Array
• Default: ['typescript`]
• Environment variable: JITI_NATIVE_MODULES

List of modules (within node_modules) to always use native require for them.

transformModules

• Type: Array
• Default: []
• Environment variable: JITI_TRANSFORM_MODULES

List of modules (within node_modules) to transform them regardless of syntax.

experimentalBun

• Type: Boolean
• Default: Enabled if process.versions.bun exists (Bun runtime)
• Environment variable: JITI_EXPERIMENTAL_BUN

Enable experimental native Bun support for transformations.

Development

• Clone this repository
• Enable Corepack using corepack enable
• Install dependencies using pnpm install
• Run pnpm dev
• Run pnpm jiti ./test/path/to/file.ts

License

Published under the MIT license. Made by @pi0 and community 💛