1 files changed, 14 insertions, 0 deletions
diff --git a/packages/browser/src/helpers/isValidDomain.ts b/packages/browser/src/helpers/isValidDomain.ts
new file mode 100644
index 0000000..4d2eedd
--- /dev/null
+++ b/packages/browser/src/helpers/isValidDomain.ts
@@ -0,0 +1,14 @@
+/**
+ * A simple test to determine if a hostname is a properly-formatted domain name
+ *
+ * A "valid domain" is defined here: https://url.spec.whatwg.org/#valid-domain
+ *
+ * Regex sourced from here:
+ * https://www.oreilly.com/library/view/regular-expressions-cookbook/9781449327453/ch08s15.html
+ */
+export function isValidDomain(hostname: string): boolean {
+  return (
+    // Consider localhost valid as well since it's okay wrt Secure Contexts
+    hostname === 'localhost' || /^([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,}$/i.test(hostname)
+  );
+}