M6: app.runtimeHighlight asks once, for the setting a script ends with, under the request cap

crates/js/src/lib.rs

@@ -690,7 +690,10 @@ fn set_runtime_highlight(_: &JsValue, args: &[JsValue], ctx: &mut Context) -> Js
     let mut h = host(ctx)?.borrow_mut();
     if h.doc.highlight != on {
         h.doc.highlight = on;
-        h.requests.push(Request::Highlight(on));
+        // Only the setting the script ends with matters: one request, the latest, under the
+        // host's request cap like any other.
+        h.requests.retain(|r| !matches!(r, Request::Highlight(_)));
+        h.request(Request::Highlight(on));
     }
     Ok(JsValue::undefined())
 }

crates/js/src/tests.rs

@@ -1560,6 +1560,10 @@ mod runtime_highlight {
         assert_eq!(o.error, None);
         assert_eq!(o.value, "false,true", "the script reads back what it set");
         assert_eq!(o.requests, vec![Request::Highlight(true)]);
+        // A script that toggles it over and over asks once, for where it ended.
+        let o = go("for (var i = 0; i < 5001; i++) { app.runtimeHighlight = !app.runtimeHighlight; }", &ev);
+        assert_eq!(o.error, None);
+        assert_eq!(o.requests, vec![Request::Highlight(true)], "one request, the last setting");
     }
 
     /// The same in XFA scripts, where the change is an effect; nothing is asked for when the