feat(html): add aria-labelledby helper

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

docs/architecture.md

@@ -36,6 +36,7 @@ Accessibility-oriented helpers are also provided for common attribute patterns:
 
 - `AriaLabel(node, label)`
 - `AriaDescribedBy(node, ids...)`
+- `AriaLabelledBy(node, ids...)`
 - `Role(node, role)`
 - `Alt(node, text)`
 - `AriaHidden(node, hidden)`

node.go

@@ -175,6 +175,12 @@ func AriaDescribedBy(n Node, ids ...string) Node {
 	return Attr(n, "aria-describedby", strings.Join(ids, " "))
 }
 
+// AriaLabelledBy sets the aria-labelledby attribute on an element node.
+// Multiple IDs are joined with spaces, matching the HTML attribute format.
+func AriaLabelledBy(n Node, ids ...string) Node {
+	return Attr(n, "aria-labelledby", strings.Join(ids, " "))
+}
+
 // Role sets the role attribute on an element node.
 func Role(n Node, role string) Node {
 	return Attr(n, "role", role)

node_test.go

@@ -252,6 +252,16 @@ func TestAriaDescribedByHelper(t *testing.T) {
 	}
 }
 
+func TestAriaLabelledByHelper(t *testing.T) {
+	ctx := NewContext()
+	node := AriaLabelledBy(El("input"), "label-1", "label-2")
+	got := node.Render(ctx)
+	want := `<input aria-labelledby="label-1 label-2">`
+	if got != want {
+		t.Errorf("AriaLabelledBy() = %q, want %q", got, want)
+	}
+}
+
 func TestRoleHelper(t *testing.T) {
 	ctx := NewContext()
 	node := Role(El("button", Raw("menu")), "navigation")