Allow providing a DOM identifier as a target for Wasm

winit/src/application.rs

@@ -137,6 +137,9 @@ where
         runtime.enter(|| A::new(flags))
     };
 
+    #[cfg(target_arch = "wasm32")]
+    let target = settings.window.platform_specific.target.clone();
+
     let builder = settings.window.into_builder(
         &application.title(),
         event_loop.primary_monitor(),
@@ -159,10 +162,16 @@ where
         let document = window.document().unwrap();
         let body = document.body().unwrap();
 
-        let _ = match body.query_selector("#iced_root").unwrap() {
-            Some(e) => body
-                .replace_child(&canvas, &e)
-                .expect("Could not replace iced_root"),
+        let target = target.and_then(|target| {
+            body.query_selector(&format!("#{}", target))
+                .ok()
+                .unwrap_or(None)
+        });
+
+        let _ = match target {
+            Some(node) => node
+                .replace_child(&canvas, &node)
+                .expect(&format!("Could not replace #{}", node.id())),
             None => body
                 .append_child(&canvas)
                 .expect("Append canvas to HTML body"),