make Map.create take Brr.El

example/dune

@@ -1,7 +1,7 @@
 (executable
  (name main)
  (modules main)
- (libraries leaflet)
+ (libraries brr leaflet)
  (modes js)
  (preprocess
   (pps js_of_ocaml-ppx)))

example/main.ml

@@ -1,7 +1,11 @@
 (* create map *)
 let map =
-  let container_id = "map" in
+  let container =
-  Leaflet.Map.create container_id
+    match Brr.Document.find_el_by_id Brr.G.document (Jstr.of_string "map") with
+    | None -> failwith "map container not found"
+    | Some el -> el
+  in
+  Leaflet.Map.create container
 
 (* setup map *)
 let () =

src/map.ml

@@ -6,8 +6,10 @@ let of_jv = Fun.id
 
 let to_jv = Fun.id
 
-let create ?(options = Jv.null) container_id =
+let create ?(options = Jv.null) container =
-  Jv.call Global.leaflet "map" [| Jv.of_string container_id; options |]
+  match Brr.El.at (Jstr.of_string "id") container with
+  | None -> failwith "container doesn't have id"
+  | Some id -> Jv.call Global.leaflet "map" [| Jv.of_jstr id; options |]
 
 let invalidate_size map =
   let (_ : Jv.t) = Jv.call map "invalidateSize" [| Jv.true' |] in

src/map.mli

@@ -2,7 +2,7 @@
 
 type t
 
-val create : ?options:Jv.t -> string -> t
+val create : ?options:Jv.t -> Brr.El.t -> t
 
 val invalidate_size : t -> unit