TypeScript execution and REPL for node.js, with source map support. Works with
typescript@>=2.7.
The latest documentation can also be found on our website: https://typestrong.org/ts-node
Native ESM support is currently experimental. For usage, limitations, and to provide feedback, see #1007.
- Overview
- Installation
- Usage
- Configuration
- Options
- CommonJS vs native ECMAScript modules
- Troubleshooting
- Make it fast
- Advanced
- Recipes
- License
ts-node is a TypeScript execution engine and REPL for Node.js.
It JIT transforms TypeScript into JavaScript, enabling you to directly execute TypeScript on Node.js without precompiling. This is accomplished by hooking node's module loading APIs, enabling it to be used seamlessly alongside other Node.js tools and libraries.
- Automatic sourcemaps in stack traces
- Automatic
tsconfig.jsonparsing - Automatic defaults to match your node version
- Typechecking (optional)
- REPL
- Write standalone scripts
- Native ESM loader
- Use third-party transpilers
- Use custom transformers
- Integrate with test runners, debuggers, and CLI tools
- Compatible with pre-compilation for production
# Locally in your project.
npm install -D typescript
npm install -D ts-node
# Or globally with TypeScript.
npm install -g typescript
npm install -g ts-node
# Depending on configuration, you may also need these
npm install -D tslib @types/nodeTip: Installing modules locally allows you to control and share the versions through package.json. TS Node will always resolve the compiler from cwd before checking relative to its own installation.
# Execute a script as `node` + `tsc`.
ts-node script.ts
# Starts a TypeScript REPL.
ts-node
# Execute code with TypeScript.
ts-node -e 'console.log("Hello, world!")'
# Execute, and print, code with TypeScript.
ts-node -p -e '"Hello, world!"'
# Pipe scripts to execute with TypeScript.
echo 'console.log("Hello, world!")' | ts-node
# Equivalent to ts-node --transpile-only
ts-node-transpile-only script.ts
# Equivalent to ts-node --cwd-mode
ts-node-cwd script.ts#!/usr/bin/env ts-node
console.log("Hello, world!")Passing CLI arguments via shebang is allowed on Mac but not Linux. For example, the following will fail on Linux:
#!/usr/bin/env ts-node --files
// This shebang is not portable. It only works on Mac
Instead, specify all ts-node options in your tsconfig.json.
You can require ts-node and register the loader for future requires by using require('ts-node').register({ /* options */ }). You can also use file shortcuts - node -r ts-node/register or node -r ts-node/register/transpile-only - depending on your preferences.
Note: If you need to use advanced node.js CLI arguments (e.g. --inspect), use them with node -r ts-node/register instead of the ts-node CLI.
ts-node exports a create() function that can be used to initialize a TypeScript compiler that isn't registered to require.extensions, and it uses the same code as register.
ts-node supports a variety of options which can be specified via tsconfig.json, as CLI flags, as environment variables, or programmatically.
For a complete list, see Options.
ts-node CLI flags must come before the entrypoint script. For example:
$ ts-node --project tsconfig-dev.json say-hello.ts Ronald
Hello, Ronald!ts-node automatically finds and loads tsconfig.json. Most ts-node options can be specified in a "ts-node" object using their programmatic, camelCase names. We recommend this because it works even when you cannot pass CLI flags, such as node --require ts-node/register and when using shebangs.
Use --skip-project to skip loading the tsconfig.json. Use --project to explicitly specify the path to a tsconfig.json.
When searching, it is resolved using the same search behavior as tsc. By default, this search is performed relative to the entrypoint script. In --cwd-mode or if no entrypoint is specified -- for example when using the REPL -- the search is performed relative to --cwd / process.cwd().
You can use this sample configuration as a starting point:
Our bundled JSON schema lists all compatible options.
@tsconfig/bases maintains recommended configurations for several node versions.
As a convenience, these are bundled with ts-node.
{
"extends": "ts-node/node16/tsconfig.json",
// Or install directly with `npm i -D @tsconfig/node16`
"extends": "@tsconfig/node16/tsconfig.json",
}If no tsconfig.json is loaded from disk, ts-node will use the newest recommended defaults from
@tsconfig/bases compatible with your node and typescript versions.
With the latest node and typescript, this is @tsconfig/node16.
Older versions of typescript are incompatible with @tsconfig/node16. In those cases we will use an older default configuration.
When in doubt, ts-node --show-config will log the configuration being used, and ts-node -vv will log node and typescript versions.
node flags must be passed directly to node; they cannot be passed to the ts-node binary nor can they be specified in tsconfig.json
We recommend using the NODE_OPTIONS environment variable to pass options to node.
NODE_OPTIONS='--trace-deprecation --abort-on-uncaught-exception' ts-node ./index.tsAlternatively, you can invoke node directly and install ts-node via --require/-r
node --trace-deprecation --abort-on-uncaught-exception -r ts-node/register ./index.tsts-node supports --print (-p), --eval (-e), --require (-r) and --interactive (-i) similar to the node.js CLI options.
Environment variables, where available, are in ALL_CAPS
-h, --helpPrints the help text-v, --versionPrints the version.-vvprints node and typescript compiler versions, too-e, --evalEvaluate code-p, --printPrint result of--eval-i, --interactiveOpens the REPL even if stdin does not appear to be a terminal
-P, --project [path]Path to TypeScript JSON project file
Environment:TS_NODE_PROJECT--skip-projectSkip project config resolution and loading
Default:false
Environment:TS_NODE_SKIP_PROJECT-c, --cwd-modeResolve config relative to the current directory instead of the directory of the entrypoint script-O, --compiler-options [opts]JSON object to merge with compiler options
Environment:TS_NODE_COMPILER_OPTIONS--show-configPrint resolvedtsconfig.json, includingts-nodeoptions, and exit
-T, --transpile-onlyUse TypeScript's fastertranspileModule
Default:false
Environment:TS_NODE_TRANSPILE_ONLY--type-checkOpposite of--transpile-only
Default:true
Environment:TS_NODE_TYPE_CHECK-H, --compiler-hostUse TypeScript's compiler host API
Default:false
Environment:TS_NODE_COMPILER_HOST--filesLoadfiles,includeandexcludefromtsconfig.jsonon startup
Default:false
Environment:TS_NODE_FILES-D, --ignore-diagnostics [code]Ignore TypeScript warnings by diagnostic code
Environment:TS_NODE_IGNORE_DIAGNOSTICS
-I, --ignore [pattern]Override the path patterns to skip compilation
Default:/node_modules/
Environment:TS_NODE_IGNORE--skip-ignoreSkip ignore checks
Default:false
Environment:TS_NODE_SKIP_IGNORE-C, --compiler [name]Specify a custom TypeScript compiler
Default:typescript
Environment:TS_NODE_COMPILER--transpiler [name]Specify a third-party, non-typechecking transpiler--prefer-ts-extsRe-order file extensions so that TypeScript imports are preferred
Default:false
Environment:TS_NODE_PREFER_TS_EXTS
--log-errorLogs TypeScript errors to stderr instead of throwing exceptions
Default:false
Environment:TS_NODE_LOG_ERROR--prettyUse pretty diagnostic formatter
Default:false
Environment:TS_NODE_PRETTYTS_NODE_DEBUGEnable debug logging
-r, --require [path]Require a node module before execution--cwdBehave as if invoked in this working directory
Default:process.cwd()
Environment:TS_NODE_CWD--emitEmit output files into.ts-nodedirectory
Default:false
Environment:TS_NODE_EMIT--scopeScope compiler to files withinscopeDir. Anything outside this directory is ignored.
*Default:false
Environment:TS_NODE_SCOPE--scopeDirDirectory within which compiler is limited whenscopeis enabled.
Default: First of:tsconfig.json"rootDir" if specified, directory containingtsconfig.json, or cwd if notsconfig.jsonis loaded.
Environment:TS_NODE_SCOPE_DIRmoduleTypeOverride the module type of certain files, ignoring thepackage.json"type"field. See Module type overrides for details.
Default: obeyspackage.json"type"andtsconfig.json"module"
Can only be specified viatsconfig.jsonor API.TS_NODE_HISTORYPath to history file for REPL
Default:~/.ts_node_repl_history--no-experimental-repl-awaitDisable top-level await in REPL. Equivalent to node's--no-experimental-repl-await
Default: Enabled if TypeScript version is 3.8 or higher and target is ES2018 or higher.
Environment:TS_NODE_EXPERIMENTAL_REPL_AWAITsetfalseto disable
The API includes additional options not shown here.
TypeScript is almost always written using modern import syntax, but you can choose to either transform to CommonJS or use node's native ESM support. Configuration is different for each.
Here is a brief comparison of the two.
| CommonJS | Native ECMAScript modules |
|---|---|
Write native import syntax |
Write native import syntax |
Transforms import into require() |
Does not transform import |
| Node executes scripts using the classic CommonJS loader | Node executes scripts using the new ESM loader |
Use any of:ts-node CLInode -r ts-node/registerNODE_OPTIONS="ts-node/register" noderequire('ts-node').register({/* options */}) |
Must use the ESM loader via:node --loader ts-node/esmNODE_OPTIONS="--loader ts-node/esm" node |
Transforming to CommonJS is typically simpler and more widely supported because it is older. You must remove "type": "module" from package.json and set "module": "CommonJS" in tsconfig.json.
{
// This can be omitted; commonjs is the default
"type": "commonjs"
}{
"compilerOptions": {
"module": "CommonJS"
}
}If you must keep "module": "ESNext" for tsc, webpack, or another build tool, you can set an override for ts-node.
{
"compilerOptions": {
"module": "ESNext"
},
"ts-node": {
"compilerOptions": {
"module": "CommonJS"
}
}
}Node's ESM loader hooks are experimental and subject to change. ts-node's ESM support is also experimental. They may have
breaking changes in minor and patch releases and are not recommended for production.
For complete usage, limitations, and to provide feedback, see #1007.
You must set "type": "module" in package.json and "module": "ESNext" in tsconfig.json.
{
"type": "module"
}{
"compilerOptions": {
"module": "ESNext" // or ES2015, ES2020
}
}ts-node uses sensible default configurations to reduce boilerplate while still respecting tsconfig.json if you
have one. If you are unsure which configuration is used, you can log it with ts-node --show-config. This is similar to
tsc --showConfig but includes "ts-node" options as well.
ts-node also respects your locally-installed typescript version, but global installations fallback to the globally-installed
typescript. If you are unsure which versions are used, ts-node -vv will log them.
$ ts-node -vv
ts-node v10.0.0
node v16.1.0
compiler v4.2.2
$ ts-node --show-config
{
"compilerOptions": {
"target": "es6",
"lib": [
"es6",
"dom"
],
"rootDir": "./src",
"outDir": "./.ts-node",
"module": "commonjs",
"moduleResolution": "node",
"strict": true,
"declaration": false,
"sourceMap": true,
"inlineSources": true,
"types": [
"node"
],
"stripInternal": true,
"incremental": true,
"skipLibCheck": true,
"importsNotUsedAsValues": "error",
"inlineSourceMap": false,
"noEmit": false
},
"ts-node": {
"cwd": "/d/project",
"projectSearchDir": "/d/project",
"require": [],
"project": "/d/project/tsconfig.json"
}
}It is important to differentiate between errors from ts-node, errors from the TypeScript compiler, and errors from node. It is also important to understand when errors are caused by a type error in your code, a bug in your code, or a flaw in your configuration.
Type errors from the compiler are thrown as a TSError. These are the same as errors you get from tsc.
Any error that is not a TSError is from node.js (e.g. SyntaxError), and cannot be fixed by TypeScript or ts-node. These are bugs in your code or configuration.
Your version of node may not support all JavaScript syntax supported by TypeScript. The compiler must transform this syntax via "downleveling," which is controlled by
the tsconfig "target" option. Otherwise your code will compile fine, but node will throw a SyntaxError.
For example, node 12 does not understand the ?. optional chaining operator. If you use "target": "esnext", then the following TypeScript syntax:
const bar: string | undefined = foo?.bar;will compile into this JavaScript:
const a = foo?.bar;When you try to run this code, node 12 will throw a SyntaxError. To fix this, you must switch to "target": "es2019" or lower so TypeScript transforms ?. into something node can understand.
These tricks will make ts-node faster.
It is often better to use tsc --noEmit to typecheck once before your tests run or as a lint step. In these cases, ts-node can skip typechecking.
- Enable
transpileOnlyto skip typechecking - Use our
swcintegration- This is by far the fastest option
- Avoid dynamic
require()which may trigger repeated typechecking; preferimport - Try with and without
--files; one may be faster depending on your project - Check
tsc --showConfig; make sure all executed files are included - Enable
skipLibCheck - Set a
typesarray to avoid loading unnecessary@types
ts-node works by registering hooks for .ts, .tsx, .js, and/or .jsx extensions.
Vanilla node loads .js by reading code from disk and executing it. Our hook runs in the middle, transforming code from TypeScript to JavaScript and passing the result to node for execution. This transformation will respect your tsconfig.json as if you had compiled via tsc.
.js and .jsx are only transformed when allowJs is enabled.
.tsx and .jsx are only transformed when jsx is enabled.
Warning: if a file is ignored or its file extension is not registered, node will either fail to resolve the file or will attempt to execute it as JavaScript without any transformation. This may cause syntax errors or other failures, because node does not understand TypeScript type syntax nor bleeding-edge ECMAScript features.
Warning: When
ts-nodeis used withallowJs, all non-ignored JavaScript files are transformed using the TypeScript compiler.
By default, TypeScript Node avoids compiling files in /node_modules/ for three reasons:
- Modules should always be published in a format node.js can consume
- Transpiling the entire dependency tree will make your project slower
- Differing behaviours between TypeScript and node.js (e.g. ES2015 modules) can result in a project that works until you decide to support a feature natively from node.js
You can use ts-node together with tsconfig-paths to load modules according to the paths section in tsconfig.json.
{
"ts-node": {
// Do not forget to `npm i -D tsconfig-paths`
"require": ["tsconfig-paths/register"]
}
}The official TypeScript Handbook explains the intended purpose for "paths" in "Additional module resolution flags".
The TypeScript compiler has a set of additional flags to inform the compiler of transformations that are expected to happen to the sources to generate the final output.
It is important to note that the compiler will not perform any of these transformations; it just uses these pieces of information to guide the process of resolving a module import to its definition file.
This means "paths" are intended to describe mappings that the build tool or runtime already performs, not to tell the build tool or
runtime how to resolve modules. In other words, they intend us to write our imports in a way node already understands. For this reason, ts-node does not modify node's module resolution behavior to implement "paths" mappings.
TypeScript Node does not use files, include or exclude, by default. This is because a large majority projects do not use all of the files in a project directory (e.g. Gulpfile.ts, runtime vs tests) and parsing every file for types slows startup time. Instead, ts-node starts with the script file (e.g. ts-node index.ts) and TypeScript resolves dependencies based on imports and references.
For global definitions, you can use the typeRoots compiler option. This requires that your type definitions be structured as type packages (not loose TypeScript definition files). More details on how this works can be found in the TypeScript Handbook.
Example tsconfig.json:
{
"compilerOptions": {
"typeRoots" : ["./node_modules/@types", "./typings"]
}
}Example project structure:
<project_root>/
-- tsconfig.json
-- typings/
-- <module_name>/
-- index.d.ts
Example module declaration file:
declare module '<module_name>' {
// module definitions go here
}For module definitions, you can use paths:
{
"compilerOptions": {
"baseUrl": ".",
"paths": {
"custom-module-type": ["types/custom-module-type"]
}
}
}An alternative approach for definitions of third-party libraries are triple-slash directives. This may be helpful if you prefer not to change your TypeScript compilerOptions or structure your custom type definitions when using typeRoots. Below is an example of the triple-slash directive as a relative path within your project:
/// <reference types="./types/untyped_js_lib" />
import UntypedJsLib from "untyped_js_lib"Tip: If you must use files, include, or exclude, enable --files flags or set TS_NODE_FILES=true.
Some projects require a patched typescript compiler which adds additional features. For example, ttypescript and ts-patch
add the ability to configure custom transformers. These are drop-in replacements for the vanilla typescript module and
implement the same API.
For example, to use ttypescript and ts-transformer-keys, add this to your tsconfig.json:
{
"ts-node": {
// This can be omitted when using ts-patch
"compiler": "ttypescript"
},
"compilerOptions": {
// plugin configuration is the same for both ts-patch and ttypescript
"plugins": [
{ "transform": "ts-transformer-keys/transformer" }
]
}
}In transpile-only mode, we skip typechecking to speed up execution time. You can go a step further and use a
third-party transpiler to transform TypeScript into JavaScript even faster. You will still benefit from
ts-node's automatic tsconfig.json discovery, sourcemap support, and global ts-node CLI. Integrations
can automatically derive an appropriate configuration from your existing tsconfig.json which simplifies project
boilerplate.
What is the difference between a compiler and a transpiler?
For our purposes, a compiler implements TypeScript's API and can perform typechecking. A third-party transpiler does not. Both transform TypeScript into JavaScript.
We have bundled an experimental swc integration.
swc is a TypeScript-compatible transpiler implemented in Rust. This makes it an order of magnitude faster
than transpileModule.
To use it, first install @swc/core or @swc/wasm. If using importHelpers, also install @swc/helpers.
npm i -D @swc/core @swc/helpersThen add the following to your tsconfig.json.
{
"ts-node": {
"transpileOnly": true,
"transpiler": "ts-node/transpilers/swc-experimental"
}
}
swcuses@swc/helpersinstead oftslib. If you have enabledimportHelpers, you must also install@swc/helpers.
To write your own transpiler integration, check our API docs.
Integrations are require()d, so they can be published to npm. The module must export a create function matching the
TranspilerModule interface.
When deciding between CommonJS and native ECMAScript modules, ts-node defaults to matching vanilla node and tsc
behavior. This means TypeScript files are transformed according to your tsconfig.json "module" option and executed
according to node's rules for the package.json "type" field.
In some projects you may need to override this behavior for some files. For example, in a webpack
project, you may have package.json configured with "type": "module" and tsconfig.json with
"module": "esnext". However, webpack uses our CommonJS hook to execute your webpack.config.ts,
so you need to force your webpack config and any supporting scripts to execute as CommonJS.
In these situations, our moduleTypes option lets you override certain files, forcing execution as
CommonJS or ESM. Node supports similar overriding via .cjs and .mjs file extensions, but .ts files cannot use them.
moduleTypes achieves the same effect, and also overrides your tsconfig.json "module" config appropriately.
The following example tells ts-node to execute a webpack config as CommonJS:
{
"ts-node": {
"transpileOnly": true,
"moduleTypes": {
"webpack.config.ts": "cjs",
// Globs are also supported with the same behavior as tsconfig "include"
"webpack-config-scripts/**/*": "cjs"
}
},
"compilerOptions": {
"module": "es2020",
"target": "es2020"
}
}Each key is a glob pattern with the same syntax as tsconfig's "include" array.
When multiple patterns match the same file, the last pattern takes precedence.
cjsoverrides matches files to compile and execute as CommonJS.esmoverrides matches files to compile and execute as native ECMAScript modules.packageresets either of the above to default behavior, which obeyspackage.json"type"andtsconfig.json"module"options.
Files with an overridden module type are transformed with the same limitations as isolatedModules. This will only affect rare cases such as using const enums with preserveConstEnums disabled.
This feature is meant to facilitate scenarios where normal compilerOptions and package.json configuration is not possible. For example, a webpack.config.ts cannot be given its own package.json to override "type". Wherever possible you should favor using traditional package.json and tsconfig.json configurations.
TypeScript Node compiles source code via require(), watching files and code reloads are out of scope for the project. If you want to restart the ts-node process on file change, existing node.js tools such as nodemon, onchange and node-dev work.
There's also ts-node-dev, a modified version of node-dev using ts-node for compilation that will restart the process on file change.
Assuming you are configuring AVA via your package.json, add one of the following configurations.
Use this configuration if your package.json does not have "type": "module".
{
"ava": {
"extensions": [
"ts"
],
"require": [
"ts-node/register"
]
}
}This configuration is necessary if your package.json has "type": "module".
{
"ava": {
"extensions": {
"ts": "module"
},
"nonSemVerExperiments": {
"configurableModuleFormat": true
},
"nodeArguments": [
"--loader=ts-node/esm"
]
}
}ts-node support is built-in to gulp.
# Create a `gulpfile.ts` and run `gulp`.
gulpSee also: https://gulpjs.com/docs/en/getting-started/javascript-and-gulpfiles#transpilation
Create a new Node.js configuration and add -r ts-node/register to "Node parameters."
Note: If you are using the --project <tsconfig.json> command line argument as per the Configuration Options, and want to apply this same behavior when launching in IntelliJ, specify under "Environment Variables": TS_NODE_PROJECT=<tsconfig.json>.
mocha --require ts-node/register --extensions ts,tsx --watch --watch-files src 'tests/**/*.{ts,tsx}' [...args]Or specify options via your mocha config file.
{
// Specify "require" for CommonJS
"require": "ts-node/register",
// Specify "loader" for native ESM
"loader": "ts-node/esm",
"extensions": ["ts", "tsx"],
"spec": [
"tests/**/*.spec.*"
],
"watch-files": [
"src"
]
}See also: https://mochajs.org/#configuring-mocha-nodejs
mocha --require ts-node/register --watch-extensions ts,tsx "test/**/*.{ts,tsx}" [...args]Note: --watch-extensions is only used in --watch mode.
ts-node node_modules/tape/bin/tape [...args]Create a new node.js configuration, add -r ts-node/register to node args and move the program to the args list (so VS Code doesn't look for outFiles).
{
"type": "node",
"request": "launch",
"name": "Launch Program",
"runtimeArgs": [
"-r",
"ts-node/register"
],
"args": [
"${workspaceFolder}/index.ts"
]
}Note: If you are using the --project <tsconfig.json> command line argument as per the Configuration Options, and want to apply this same behavior when launching in VS Code, add an "env" key into the launch configuration: "env": { "TS_NODE_PROJECT": "<tsconfig.json>" }.
In many cases, setting NODE_OPTIONS will enable ts-node within other node tools, child processes, and worker threads.
NODE_OPTIONS="-r ts-node/register"Or, if you require native ESM support:
NODE_OPTIONS="--loader ts-node/esm"This tells any node processes which receive this environment variable to install ts-node's hooks before executing other code.
ts-node is licensed under the MIT license. MIT
ts-node includes source code from Node.js which is licensed under the MIT license. Node.js license information
ts-node includes source code from the TypeScript compiler which is licensed under the Apache License 2.0. TypeScript license information
{ // This is an alias to @tsconfig/node12: https://github.com/tsconfig/bases "extends": "ts-node/node12/tsconfig.json", // Most ts-node options can be specified here using their programmatic names. "ts-node": { // It is faster to skip typechecking. // Remove if you want ts-node to do typechecking. "transpileOnly": true, "files": true, "compilerOptions": { // compilerOptions specified here will override those declared below, // but *only* in ts-node. Useful if you want ts-node and tsc to use // different options with a single tsconfig.json. } }, "compilerOptions": { // typescript options here } }