diff --git a/reactiveweb/src/when-changed.ts b/reactiveweb/src/when-changed.ts
new file mode 100644
index 0000000..6c83ef6
--- /dev/null
+++ b/reactiveweb/src/when-changed.ts
@@ -0,0 +1,6 @@
+export function whenChanged({ ifDifferent, equals, do }) {
+  // TODO:
+  // - when deeplyDifferent (from ifDifferent)
+  //   - using equals
+  //   - call do
+}