TypeScript — Hello World
The classic hello-world in TypeScript (shipped as .mts to avoid the MPEG-TS .ts collision) — a typed function for testing TypeScript-aware highlighters and the tsc compiler.
// The classic first program, in TypeScript.
function greet(name: string): string {
return `Hello, ${name}!`;
}
console.log(greet("world"));
Specifications
- Language
- TypeScript
- Kind
- hello-world
- Lines
- 6
- Encoding
- UTF-8
- Line Endings
- LF
Testing contract
Expected to pass- Scenario
- Type-check the file with tsc and then run the emitted JavaScript.
- Expected result
- It type-checks with no diagnostics under `strict: true` and prints exactly `Hello, world!`. The `.mts` extension is load-bearing: it forces ES-module resolution and keeps the file clear of the MPEG-TS `.ts` collision.
What is a .mts file?
TypeScript (.mts) is a plain-text source file for TypeScript — a statically typed superset of JavaScript that compiles to plain JS. The .mts extension specifically marks an ES-module TypeScript file. It adds interfaces, generics, enums, and type annotations on top of JavaScript syntax.
How to use this file
Use an example .mts file to test TypeScript-aware highlighters, the tsc compiler and type checker, ESLint with the TS parser, and editor tooling. (We ship TypeScript as .mts to avoid the MPEG-TS .ts extension collision.)
How to use this file for testing
“TypeScript — Hello World” is a deterministic Novus Examples fixture for Syntax highlighting, Code parsing, Editor testing. Idiomatic hello-world programs and realistic snippets across sixteen languages, exercising comments, string escapes, interpolation, numeric literals, and language keywords — for testing syntax highlighters, editor themes, and tree-sitter grammars.
Documented properties for this file: TypeScript · UTF-8 · LF. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
This is a short, known-correct source file. Run it through your syntax highlighter, linter, formatter, tree-sitter grammar, or parser, and open it in the in-browser editor to tweak and re-download. Each snippet exercises comments, string escapes, literals, and language keywords.
Code examples
npx tsx hello-world.mts # or: deno run hello-world.mtsRelated files
- mtsTypeScript — Shapes (union, generics, enum)A realistic TypeScript snippet with an enum, a discriminated union, generics, exhaustive switch handling, and a typed reduce — for testing the type checker, highlighters, and the TS ESLint parser.
- mtsTypescript Lint Invalid — Any Cast InvalidIntentionally lint-bait SAMPLE typescript snippet (any-cast-invalid) for rule-engine tests.
- mtsTypeScript SatisfiesTypeScript satisfies operator sample (.mts) for TS tooling.
- cC — Hello WorldThe classic hello-world in C — an include, main, and printf — for testing highlighters, C compilers, and parsers against the canonical first program.
- cC — Linked list (structs, malloc, pointers)A realistic C program: a singly linked list with a typedef struct, malloc/free memory management, pointer walking, and error handling — for testing highlighters, compilers, and static analysers.
- cC StructC struct SAMPLE for clangd / highlighter fixtures.
Generated by generation/code_samples.py. Free for any use, no attribution required — license.