JavaScript — Hello World
The classic hello-world in modern JavaScript — a minimal function calling console.log, for testing highlighters, Node, and JS parsers.
// The classic first program, in modern JavaScript.
function main() {
console.log("Hello, world!");
}
main();
Specifications
- Language
- JavaScript
- Kind
- hello-world
- Lines
- 6
- Encoding
- UTF-8
- Line Endings
- LF
Testing contract
Expected to pass- Scenario
- Execute the file in Node or any ES2015+ engine and capture stdout.
- Expected result
- It prints exactly `Hello, world!` and a newline. There are no imports, no exports and no globals other than console, so it also runs unchanged inside a `<script>` tag.
What is a .js file?
JavaScript (.js) is a plain-text source file for the JavaScript language — the scripting language of the web, also used server-side via Node.js. It is dynamically typed and event-driven, with first-class functions, prototypes, and (in modern syntax) modules, classes, and async/await.
How to use this file
Use an example .js file to test syntax highlighters, linters (ESLint), formatters (Prettier), bundlers, and JavaScript parsers, or as editor and diff-viewer fixtures.
How to use this file for testing
“JavaScript — 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: JavaScript · 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
node hello-world.jsRelated files
- jsJavaScript — To-do list (class, private fields, async)A realistic JavaScript snippet with an ES class, private #fields, arrow functions, template literals, a getter, and async/await — for testing highlighters, ESLint, Prettier, and bundlers.
- jsJavascript Lint Invalid — Eqeqeq InvalidIntentionally lint-bait SAMPLE javascript snippet (eqeqeq-invalid) for rule-engine tests.
- jsJavascript Lint Invalid — Var Shadow InvalidIntentionally lint-bait SAMPLE javascript snippet (var-shadow-invalid) for rule-engine tests.
- 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.