diff --git a/src/syscall/js/js.go b/src/syscall/js/js.go
index 19cdedc309ad6e..885723f87d690b 100644
--- a/src/syscall/js/js.go
+++ b/src/syscall/js/js.go
@@ -114,6 +114,8 @@ func Global() Value {
 //  | string                 | string                 |
 //  | []interface{}          | new array              |
 //  | map[string]interface{} | new object             |
+//
+// Panics if x is not one of the expected types.
 func ValueOf(x interface{}) Value {
 	switch x := x.(type) {
 	case Value: // should precede Wrapper to avoid a loop