Pattern

Regex for GitHub issue reference

#123 or org/repo#123 reference.

The GitHub issue reference regex is (?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+ — copy it below, or open it in the explainer for a token-by-token breakdown.

The pattern

(?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+

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What it matches

#123
octocat/Hello-World#1
#9999

What it doesn't match

#
#abc
issue 123

Notes & gotchas

Matches bare issue/PR numbers (#123) and cross-repo references (owner/repo#123). Used in commit messages and comments to link related work.

Code in your language

Use the explainer's Code tab to generate ready-to-paste snippets in JavaScript, Python, Java, .NET, Go, Ruby, and PHP for this pattern.

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Token-by-token breakdown

Every part of the pattern, left to right:

Token	Meaning
`(?:`	start of a non-capturing group
`[A-Za-z0-9.-]+`	one or more: any of: uppercase letters, lowercase letters, digits, “.”, “-”
`\/`	literal “/”
`[A-Za-z0-9.-]+`	one or more: any of: uppercase letters, lowercase letters, digits, “.”, “-”
`)?`	end of group, optional (zero or one)
`#`	literal text “#”
`\d+`	one or more: digit (0–9)

About this pattern

Developer-oriented patterns help with code analysis, log parsing, and data transformation. Use these in build scripts, CI tools, IDE search-and-replace, and code review utilities.

Quick usage in different languages

This exact pattern — with the correct escaping and idioms for each language:

JavaScript: /(?:[A-Za-z0-9.-]+\\/[A-Za-z0-9.-]+)?#\d+/.test(value)
Python: re.match(r"(?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+", value)
Java: Pattern.compile("(?:[A-Za-z0-9.-]+\\/[A-Za-z0-9.-]+)?#\\d+").matcher(value).matches()
C# / .NET: Regex.IsMatch(value, @"(?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+")
Go: regexp.MustCompile(`(?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+`).MatchString(value)
Ruby: /(?:[A-Za-z0-9.-]+\\/[A-Za-z0-9.-]+)?#\d+/.match?(value)
PHP: preg_match('~(?:[A-Za-z0-9.-]+\/[A-Za-z0-9.-]+)?#\d+~', $value)

The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.

Common pitfalls

Not anchored. Without ^ and $ this can match a substring anywhere in the input — add anchors if you need the whole value to conform.
ASCII letters only. [a-zA-Z] excludes accented and non-Latin letters (é, ü, ß, ñ, and non-Latin scripts). For international input use Unicode properties like \p{L} with the u flag.
Escape it correctly per language. In Java and JavaScript strings each backslash must be doubled (\\d); in Python, Go, and C# use raw/verbatim strings so the backslashes survive.
Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the github issue reference against a source of truth (database, API, or checksum) where it matters.

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