diff --git a/src/matcher.mjs b/src/matcher.mjs
new file mode 100644
index 0000000..1387d88
--- /dev/null
+++ b/src/matcher.mjs
@@ -0,0 +1,6 @@
+export function nameExtensionMatcher(extensions) {
+  const r = new RegExp(
+    `(${extensions.map(x => x.replace(/\./, "\\.")).join("|")})$`
+  );
+  return entry => r.test(entry.name);
+}