ts-node TypeScript: Methods, Examples, Installation |…

What is ts-node and why is it needed?

ts-node is a TypeScript engine for Node.js that allows you to run TypeScript files directly, without prior compilation to JavaScript. It works as a REPL (Read-Eval-Print Loop) and as a command-line tool, providing seamless integration of TypeScript into the Node.js ecosystem.

Main use cases:

Fast development and prototyping — no need to wait for compilation on every change
Running scripts — executing TypeScript files in production (with caution)
Testing — running tests written in TypeScript
Interactive development — REPL mode for experimenting with TypeScript
Project migration — gradual transition from JavaScript to TypeScript

Unlike the standard approach (compilation via tsc and running via node), ts-node makes the development process smoother and faster.

Installing ts-node

Installation is done via npm (Node.js package manager). For Python developers: this is analogous to pip install.

# Global installation (available everywhere)npm install -g ts-node

# Local installation (recommended for projects)npm install --save-dev ts-node

# Installation together with TypeScript (if not already installed)npm install --save-dev ts-node typescript

# For working with specific TypeScript versionsnpm install --save-dev ts-node@10.9.2 typescript@5.3.3

After installation, check the version:

ts-node --version# Output: v10.9.2

Quick start with a code example

Create a file hello.ts:

// hello.tsinterface Greeting {    name: string;    age: number;}

function greet(person: Greeting): string {    return `Hello, ${person.name}! You are ${person.age} years old.`;}

const user: Greeting = { name: "Alexey", age: 30 };console.log(greet(user));

Run without compilation:

ts-node hello.ts# Output: Hello, Alexey! You are 30 years old.

For comparison, the usual method would take two steps:

tsc hello.ts    # compilation to hello.jsnode hello.js   # running the compiled file

Main methods and functions of ts-node

1. `ts-node [file.ts]` — Basic file execution

Description: The main command for executing a TypeScript file. ts-node automatically compiles and runs the code.

Parameters:

file.ts — path to the TypeScript file
--project or -P — path to tsconfig.json
--transpile-only — transpilation only (faster, but without type checking)

Example:

# Normal executionts-node app.ts

# With configuration specifiedts-node --project tsconfig.prod.json app.ts

# Transpile only (faster)ts-node --transpile-only app.ts

2. `ts-node --eval` — Execute code from a string

Description: Allows you to execute TypeScript code passed as a string, without creating a file.

Parameters:

-e or --eval — string with TypeScript code
-p or --print — print the execution result

Example:

# Simple expressionts-node -e "console.log('Hello from ts-node!')"

# Using TypeScript featurests-node -e "interface User { name: string }const user: User = { name: 'Maria' };console.log(user.name);"

# With result outputts-node -p "1 + 2"