feat: add eval_with_callback to Webview and WebviewWindow (#14925)

* feat: add `eval_with_callback` to Webview and WebviewWindow

* docs: fix eval_with_callback docs and add change file

---------

Co-authored-by: Tony <68118705+Legend-Master@users.noreply.github.com>

Author: lanyeeee

.changes/eval-with-callback.md

@@ -0,0 +1,7 @@
+---
+'tauri': 'minor:feat'
+'tauri-runtime': 'minor:feat'
+'tauri-runtime-wry': 'minor:feat'
+---
+
+Add `eval_with_callback` to the Tauri webview APIs and runtime dispatch layers.

crates/tauri-runtime-wry/src/lib.rs

@@ -1475,6 +1475,15 @@ pub enum WebviewMessage {
   EvaluateScript(String),
   #[cfg(all(feature = "tracing", not(target_os = "android")))]
   EvaluateScript(String, Sender<()>, tracing::Span),
+  #[cfg(not(all(feature = "tracing", not(target_os = "android"))))]
+  EvaluateScriptWithCallback(String, Box<dyn Fn(String) + Send + 'static>),
+  #[cfg(all(feature = "tracing", not(target_os = "android")))]
+  EvaluateScriptWithCallback(
+    String,
+    Box<dyn Fn(String) + Send + 'static>,
+    Sender<()>,
+    tracing::Span,
+  ),
   CookiesForUrl(Url, Sender<Result<Vec<tauri_runtime::Cookie<'static>>>>),
   Cookies(Sender<Result<Vec<tauri_runtime::Cookie<'static>>>>),
   SetCookie(tauri_runtime::Cookie<'static>),
@@ -1830,6 +1839,46 @@ impl<T: UserEvent> WebviewDispatch<T> for WryWebviewDispatcher<T> {
     )
   }
 
+  #[cfg(all(feature = "tracing", not(target_os = "android")))]
+  fn eval_script_with_callback<S: Into<String>>(
+    &self,
+    script: S,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> Result<()> {
+    // use a channel so the EvaluateScript task uses the current span as parent
+    let (tx, rx) = channel();
+    getter!(
+      self,
+      rx,
+      Message::Webview(
+        *self.window_id.lock().unwrap(),
+        self.webview_id,
+        WebviewMessage::EvaluateScriptWithCallback(
+          script.into(),
+          Box::new(callback),
+          tx,
+          tracing::Span::current(),
+        ),
+      )
+    )
+  }
+
+  #[cfg(not(all(feature = "tracing", not(target_os = "android"))))]
+  fn eval_script_with_callback<S: Into<String>>(
+    &self,
+    script: S,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> Result<()> {
+    send_user_message(
+      &self.context,
+      Message::Webview(
+        *self.window_id.lock().unwrap(),
+        self.webview_id,
+        WebviewMessage::EvaluateScriptWithCallback(script.into(), Box::new(callback)),
+      ),
+    )
+  }
+
   fn set_zoom(&self, scale_factor: f64) -> Result<()> {
     send_user_message(
       &self.context,
@@ -3712,6 +3761,20 @@ fn handle_user_message<T: UserEvent>(
               log::error!("{e}");
             }
           }
+          #[cfg(all(feature = "tracing", not(target_os = "android")))]
+          WebviewMessage::EvaluateScriptWithCallback(script, callback, tx, span) => {
+            let _span = span.entered();
+            if let Err(e) = webview.evaluate_script_with_callback(&script, callback) {
+              log::error!("{e}");
+            }
+            tx.send(()).unwrap();
+          }
+          #[cfg(not(all(feature = "tracing", not(target_os = "android"))))]
+          WebviewMessage::EvaluateScriptWithCallback(script, callback) => {
+            if let Err(e) = webview.evaluate_script_with_callback(&script, callback) {
+              log::error!("{e}");
+            }
+          }
           WebviewMessage::Navigate(url) => {
             if let Err(e) = webview.load_url(url.as_str()) {
               log::error!("failed to navigate to url {}: {}", url, e);

crates/tauri-runtime/src/lib.rs

@@ -590,6 +590,16 @@ pub trait WebviewDispatch<T: UserEvent>: Debug + Clone + Send + Sync + Sized + '
   /// Executes javascript on the window this [`WindowDispatch`] represents.
   fn eval_script<S: Into<String>>(&self, script: S) -> Result<()>;
 
+  /// Evaluate JavaScript with callback function on the webview this [`WebviewDispatch`] represents.
+  /// The evaluation result will be serialized into a JSON string and passed to the callback function.
+  ///
+  /// Exception is ignored because of the limitation on Windows. You can catch it yourself and return as string as a workaround.
+  fn eval_script_with_callback<S: Into<String>>(
+    &self,
+    script: S,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> Result<()>;
+
   /// Moves the webview to the given window.
   fn reparent(&self, window_id: WindowId) -> Result<()>;
 

crates/tauri/src/test/mock_runtime.rs

@@ -593,6 +593,19 @@ impl<T: UserEvent> WebviewDispatch<T> for MockWebviewDispatcher {
     Ok(())
   }
 
+  fn eval_script_with_callback<S: Into<String>>(
+    &self,
+    script: S,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> Result<()> {
+    self
+      .last_evaluated_script
+      .lock()
+      .unwrap()
+      .replace(script.into());
+    Ok(())
+  }
+
   fn url(&self) -> Result<String> {
     Ok(self.url.lock().unwrap().clone())
   }

crates/tauri/src/webview/mod.rs

@@ -1896,6 +1896,22 @@ tauri::Builder::default()
       .map_err(Into::into)
   }
 
+  /// Evaluate JavaScript with callback function on this webview.
+  /// The evaluation result will be serialized into a JSON string and passed to the callback function.
+  ///
+  /// Exception is ignored because of the limitation on Windows. You can catch it yourself and return as string as a workaround.
+  pub fn eval_with_callback(
+    &self,
+    js: impl Into<String>,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> crate::Result<()> {
+    self
+      .webview
+      .dispatcher
+      .eval_script_with_callback(js.into(), callback)
+      .map_err(Into::into)
+  }
+
   /// Register a JS event listener and return its identifier.
   pub(crate) fn listen_js(
     &self,

crates/tauri/src/webview/webview_window.rs

@@ -2363,6 +2363,18 @@ impl<R: Runtime> WebviewWindow<R> {
     self.webview.eval(js)
   }
 
+  /// Evaluate JavaScript with callback function on this webview.
+  /// The evaluation result will be serialized into a JSON string and passed to the callback function.
+  ///
+  /// Exception is ignored because of the limitation on Windows. You can catch it yourself and return as string as a workaround.
+  pub fn eval_with_callback(
+    &self,
+    js: impl Into<String>,
+    callback: impl Fn(String) + Send + 'static,
+  ) -> crate::Result<()> {
+    self.webview.eval_with_callback(js, callback)
+  }
+
   /// Opens the developer tools window (Web Inspector).
   /// The devtools is only enabled on debug builds or with the `devtools` feature flag.
   ///