Running TS — tsx / ts-node

For "I want to run a TypeScript file like it's JavaScript" you need a runner. The modern choice is tsx — fast, zero config, and based on esbuild.

Install & use

pnpm add -D tsx

tsx src/index.ts                # run once
tsx watch src/index.ts          # restart on change
node --import tsx src/index.ts  # via Node's --import flag

Use in scripts

{
    "scripts": {
        "dev":   "tsx watch src/index.ts",
        "start": "tsx src/index.ts",
        "seed":  "tsx scripts/seed.ts"
    }
}

Other runners

Node 22's native TS support

node --experimental-strip-types script.ts

Strips type annotations and runs the result. No transformation of enums, decorators, or generics — those need a real compiler. Still useful for simple scripts.

Pitfalls

• tsx runs the file without type-checking. Keep tsc --noEmit in CI to catch errors.
• Some ESM features (top-level await, JSON imports) need flags depending on Node version.
• Globals from @types/node are visible if installed — they don't run, they just type-check.

Example

// 2020s: use 'tsx' — fast and zero-config
//   pnpm add -D tsx
//   tsx src/index.ts
//
// ts-node still works but tsx (esbuild under the hood) is faster.
// Node 22+ also runs *.ts files natively with --experimental-strip-types.
console.log('tsx = node + TypeScript = instant');

Exercise

Test yourself