Identifiersflags: g

GitHub Actions Expression

Match `${{ expression }}` interpolations used in GitHub Actions workflow YAML.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("\\$\\{\\{\\s*([^}]+?)\\s*\\}\\}", "g");
const input = "if: ${{ github.actor == 'octocat' }}";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

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

Python (re) code

pyPython

import re

pattern = re.compile(r"\$\{\{\s*([^}]+?)\s*\}\}")
input_text = "if: ${{ github.actor == 'octocat' }}"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`\$\{\{\s*([^}]+?)\s*\}\}`)
	input := `if: ${{ github.actor == 'octocat' }}`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

\$\{\{\s*([^}]+?)\s*\}\}   (flags: g)

Raw source: \$\{\{\s*([^}]+?)\s*\}\}

How it works

\$\{\{ matches the literal `${{`. \s*([^}]+?)\s* lazily captures the inner expression (with surrounding whitespace stripped). \}\} matches the closing `}}`. The lazy quantifier prevents accidentally consuming through to a later `}}` in the same line.