feat(window): add is_focused API (#407)

plugins/window/guest-js/index.ts

@@ -563,6 +563,24 @@ class WindowManager extends WebviewWindowHandle {
     });
   }
 
+  /**
+   * Gets the window's current focus state.
+   * @example
+   * ```typescript
+   * import { appWindow } from '@tauri-apps/plugin-window';
+   * const focused = await appWindow.isFocused();
+   * ```
+   *
+   * @returns Whether the window is focused or not.
+   *
+   * @since 2.0.0
+   * */
+  async isFocused(): Promise<boolean> {
+    return window.__TAURI_INVOKE__("plugin:window|is_focused", {
+      label: this.label,
+    });
+  }
+
   /**
    * Gets the window's current decorated state.
    * @example
@@ -1779,6 +1797,27 @@ class WebviewWindow extends WindowManager {
     }
     return null;
   }
+
+  /**
+   *  Gets the focused window.
+   * @example
+   * ```typescript
+   * import { WebviewWindow } from '@tauri-apps/plugin-window';
+   * const focusedWindow = WebviewWindow.getFocusedWindow();
+   * ```
+   *
+   * @returns The WebviewWindow instance to communicate with the webview or `undefined` if there is not any focused window.
+   *
+   * @since 1.4
+   */
+  static async getFocusedWindow(): Promise<WebviewWindow | null> {
+    for (const w of getAll()) {
+      if (await w.isFocused()) {
+        return w;
+      }
+    }
+    return null;
+  }
 }
 
 /** The WebviewWindow for the current window. */