JavaScript / ECMAScript

Keep-a-Changelog Entry Header in JS

Match Keep-a-Changelog style version headers like `## [1.2.3] - 2024-01-15` or `## 2.0.0`.

Try it in the JS tester →

Pattern

regexJS
^##\s+\[?([\w.\-]+)\]?(?:\s*-\s*(\d{4}-\d{2}-\d{2}))?   (flags: gm)

JavaScript / ECMAScript code

jsJavaScript
const re = new RegExp("^##\\s+\\[?([\\w.\\-]+)\\]?(?:\\s*-\\s*(\\d{4}-\\d{2}-\\d{2}))?", "gm");
const input = "## [1.2.3] - 2024-01-15\\n## [Unreleased]";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

How the pattern works

^## matches the markdown H2 marker. \s+ requires whitespace. \[? optionally matches an opening bracket. ([\w.\-]+) captures the version (semver, calendar version, or label like `Unreleased`). \]? optionally matches the closing bracket. (?:\s*-\s*(\d{4}-\d{2}-\d{2}))? optionally captures an ISO date.

Examples

Input

## [1.2.3] - 2024-01-15\n## [Unreleased]

Matches

  • ## [1.2.3] - 2024-01-15
  • ## [Unreleased]

Input

## 2.0.0 - 2025-12-25

Matches

  • ## 2.0.0 - 2025-12-25

Input

# Title

No match

—

Same pattern, other engines

Python (re)

Supported

See how this pattern looks (and behaves) in Python's stdlib `re` module.

Go (RE2)

Supported

See how this pattern looks (and behaves) in Go's `regexp` package (RE2 engine).

← Back to Keep-a-Changelog Entry Header overview (all engines)