feat(html): apply attrs through iterator wrappers

Co-Authored-By: Virgil <virgil@lethean.io>

node.go

@@ -91,7 +91,7 @@ func El(tag string, children ...Node) Node {
 
 // Attr sets an attribute on an El node. Returns the node for chaining.
 // Usage example: Attr(El("a", Text("docs")), "href", "/docs")
-// It recursively traverses through wrappers like If, Unless, and Entitled.
+// It recursively traverses through wrappers like If, Unless, Entitled, and Each.
 func Attr(n Node, key, value string) Node {
 	if n == nil {
 		return n
@@ -110,6 +110,8 @@ func Attr(n Node, key, value string) Node {
 		for _, child := range t.cases {
 			Attr(child, key, value)
 		}
+	case attrApplier:
+		t.applyAttr(key, value)
 	}
 	return n
 }
@@ -314,6 +316,10 @@ type eachNode[T any] struct {
 	fn    func(T) Node
 }
 
+type attrApplier interface {
+	applyAttr(key, value string)
+}
+
 // Each iterates items and renders each via fn.
 // Usage example: Each([]string{"a", "b"}, func(v string) Node { return Text(v) })
 func Each[T any](items []T, fn func(T) Node) Node {
@@ -330,6 +336,17 @@ func (n *eachNode[T]) Render(ctx *Context) string {
 	return n.renderWithLayoutPath(ctx, "")
 }
 
+func (n *eachNode[T]) applyAttr(key, value string) {
+	if n == nil || n.fn == nil {
+		return
+	}
+
+	prev := n.fn
+	n.fn = func(item T) Node {
+		return Attr(prev(item), key, value)
+	}
+}
+
 func (n *eachNode[T]) renderWithLayoutPath(ctx *Context, path string) string {
 	if n == nil || n.fn == nil || n.items == nil {
 		return ""

node_test.go

@@ -318,6 +318,34 @@ func TestAttr_ThroughSwitchNode_Good(t *testing.T) {
 	}
 }
 
+func TestAttr_ThroughEachNode_Good(t *testing.T) {
+	ctx := NewContext()
+	node := Each([]string{"a", "b"}, func(item string) Node {
+		return El("span", Raw(item))
+	})
+	Attr(node, "class", "item")
+
+	got := node.Render(ctx)
+	want := `<span class="item">a</span><span class="item">b</span>`
+	if got != want {
+		t.Errorf("Attr through Each = %q, want %q", got, want)
+	}
+}
+
+func TestAttr_ThroughEachSeqNode_Good(t *testing.T) {
+	ctx := NewContext()
+	node := EachSeq(slices.Values([]string{"a", "b"}), func(item string) Node {
+		return El("span", Raw(item))
+	})
+	Attr(node, "data-kind", "item")
+
+	got := node.Render(ctx)
+	want := `<span data-kind="item">a</span><span data-kind="item">b</span>`
+	if got != want {
+		t.Errorf("Attr through EachSeq = %q, want %q", got, want)
+	}
+}
+
 func TestTextNode_WithService_Good(t *testing.T) {
 	svc, _ := i18n.New()
 	ctx := NewContextWithService(svc)