Initial commit

src/index.js

@@ -0,0 +1,15 @@
+const fs = require('fs');
+
+function main() {
+  const message = process.env.INPUT_MESSAGE || '';
+  const outputPath = process.env.GITHUB_OUTPUT;
+  const line = `message=${message}\n`;
+
+  if (outputPath) {
+    fs.appendFileSync(outputPath, line);
+  } else {
+    process.stdout.write(line);
+  }
+}
+
+main();