Strip leading @ from password reset input

app/soapbox/utils/__tests__/input.test.ts

@@ -0,0 +1,7 @@
+import { normalizeUsername } from '../input';
+
+test('normalizeUsername', () => {
+  expect(normalizeUsername('@alex')).toBe('alex');
+  expect(normalizeUsername('alex@alexgleason.me')).toBe('alex@alexgleason.me');
+  expect(normalizeUsername('@alex@gleasonator.com')).toBe('alex@gleasonator.com');
+});

app/soapbox/utils/input.ts

@@ -0,0 +1,13 @@
+/** Trim the username and strip the leading @. */
+const normalizeUsername = (username: string): string => {
+  const trimmed = username.trim();
+  if (trimmed[0] === '@') {
+    return trimmed.slice(1);
+  } else {
+    return trimmed;
+  }
+};
+
+export {
+  normalizeUsername,
+};