A small code change, ready to review

What changes

The original check accepted any text containing an @ symbol. The proposed change trims surrounding spaces, rejects non-text values and checks for a simple address structure.

• Trim spaces before checking the address.
• Reject empty, malformed and non-text values.
• Add test cases for valid and invalid input.

The patch

diff --git a/src/email.mjs b/src/email.mjs
--- a/src/email.mjs
+++ b/src/email.mjs
@@ -1,3 +1,5 @@
 export function isCheckoutEmail(value) {
-  return typeof value === 'string' && value.includes('@');
+  if (typeof value !== 'string') return false;
+  const email = value.trim();
+  return /^[^@\s]+@[^@\s]+\.[^@\s]+$/.test(email);
 }
diff --git a/tests/email.test.mjs b/tests/email.test.mjs
new file mode 100644
--- /dev/null
+++ b/tests/email.test.mjs
@@ -0,0 +1,13 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { isCheckoutEmail } from '../src/email.mjs';
+
+test('accepts basic addresses with surrounding spaces', () => {
+  assert.equal(isCheckoutEmail(' person@example.com '), true);
+});
+
+test('rejects malformed or non-text values', () => {
+  for (const value of ['', '@', 'person@', 'person@example', null]) {
+    assert.equal(isCheckoutEmail(value), false);
+  }
+});

The simple check illustrates a code review. It is not a complete implementation of email validation.

How to check it

Create src/email.mjs with the original code below and place the downloaded patch in the project folder. Apply it, then run the test command. These tests cover the small example; they do not validate a checkout system or send a payment.

export function isCheckoutEmail(value) {
  return typeof value === 'string' && value.includes('@');
}

git apply checkout-fix.diff
node --test tests/email.test.mjs

The example tests were checked locally while building this sample. This page does not run code when you open it.