-

packages/utils/src/__tests__/cx.test.ts

@@ -0,0 +1,16 @@
+import { describe, it, expect } from 'vitest';
+import { cx } from '../cx';
+
+describe('cx', () => {
+  it('joins truthy strings', () => {
+    expect(cx('a', 'b', 'c')).toBe('a b c');
+  });
+
+  it('filters out falsy values', () => {
+    expect(cx('a', false, 'b', null, undefined, 'c')).toBe('a b c');
+  });
+
+  it('returns empty string when all falsy', () => {
+    expect(cx(false, null, undefined)).toBe('');
+  });
+});

packages/utils/src/cx.ts

@@ -0,0 +1,6 @@
+type ClassValue = string | false | null | undefined;
+
+/** Tiny className joiner. Filters out falsy values. */
+export function cx(...args: ClassValue[]): string {
+  return args.filter(Boolean).join(' ');
+}