feat: add updater for package.json

internal/updater/packagejson.go

@@ -0,0 +1,30 @@
+package updater
+
+import (
+	"regexp"
+	"strings"
+)
+
+// PackageJson creates an updater that modifies the version field in package.json files
+func PackageJson(info ReleaseInfo) Updater {
+	return func(content string, filename string) (string, error) {
+		if filename != "package.json" {
+			return content, nil // No update needed for non-package.json files
+		}
+		// We strip the "v" prefix to match npm versioning convention
+		version := strings.TrimPrefix(info.Version, "v")
+
+		// Regex to match "version": "..." with flexible whitespace and quote styles
+		versionRegex := regexp.MustCompile(`("version"\s*:\s*)"[^"]*"`)
+
+		// Check if the file contains a version field
+		if !versionRegex.MatchString(content) {
+			return content, nil
+		}
+
+		// Replace the version value while preserving the original formatting
+		updatedContent := versionRegex.ReplaceAllString(content, `${1}"`+version+`"`)
+
+		return updatedContent, nil
+	}
+}