Merge pull request #931 from atom/will-navigate

Add "will-navigate" event

atom/browser/api/atom_api_web_contents.cc

@@ -111,9 +111,15 @@ content::WebContents* WebContents::OpenURLFromTab(
     args.AppendString("");
     args.AppendInteger(params.disposition);
     Emit("-new-window", args);
-    return NULL;
+    return nullptr;
   }
 
+  // Give user a chance to cancel navigation.
+  base::ListValue args;
+  args.AppendString(params.url.spec());
+  if (Emit("will-navigate", args))
+    return nullptr;
+
   content::NavigationController::LoadURLParams load_url_params(params.url);
   load_url_params.referrer = params.referrer;
   load_url_params.transition_type = params.transition;

atom/browser/api/atom_api_window.cc

@@ -92,6 +92,12 @@ void Window::WillCreatePopupWindow(const base::string16& frame_name,
   Emit("-new-window", args);
 }
 
+void Window::WillNavigate(bool* prevent_default, const GURL& url) {
+  base::ListValue args;
+  args.AppendString(url.spec());
+  *prevent_default = Emit("-will-navigate", args);
+}
+
 void Window::WillCloseWindow(bool* prevent_default) {
   *prevent_default = Emit("close");
 }

atom/browser/api/atom_api_window.h

@@ -50,6 +50,7 @@ class Window : public mate::EventEmitter,
                              const GURL& target_url,
                              const std::string& partition_id,
                              WindowOpenDisposition disposition) override;
+  void WillNavigate(bool* prevent_default, const GURL& url) override;
   void WillCloseWindow(bool* prevent_default) override;
   void OnWindowClosed() override;
   void OnWindowBlur() override;

atom/browser/api/lib/browser-window.coffee

@@ -30,6 +30,10 @@ BrowserWindow::_init = ->
     options = show: true, width: 800, height: 600
     ipc.emit 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_OPEN', event, url, frameName, options
 
+  # Redirect "will-navigate" to webContents.
+  @on '-will-navigate', (event, url) =>
+    @webContents.emit 'will-navigate', event, url
+
   # Remove the window from weak map immediately when it's destroyed, since we
   # could be iterating windows before GC happened.
   @once 'closed', =>

atom/browser/native_window.cc

@@ -169,7 +169,7 @@ NativeWindow* NativeWindow::FromRenderView(int process_id, int routing_id) {
       return window;
   }
 
-  return NULL;
+  return nullptr;
 }
 
 void NativeWindow::InitFromOptions(const mate::Dictionary& options) {
@@ -370,13 +370,13 @@ void NativeWindow::CloseWebContents() {
 
 content::WebContents* NativeWindow::GetWebContents() const {
   if (!inspectable_web_contents_)
-    return NULL;
+    return nullptr;
   return inspectable_web_contents()->GetWebContents();
 }
 
 content::WebContents* NativeWindow::GetDevToolsWebContents() const {
   if (!inspectable_web_contents_)
-    return NULL;
+    return nullptr;
   return inspectable_web_contents()->devtools_web_contents();
 }
 
@@ -524,9 +524,17 @@ content::WebContents* NativeWindow::OpenURLFromTab(
                                             params.url,
                                             "",
                                             params.disposition));
-    return NULL;
+    return nullptr;
   }
 
+  // Give user a chance to prevent navigation.
+  bool prevent_default = false;
+  FOR_EACH_OBSERVER(NativeWindowObserver,
+                    observers_,
+                    WillNavigate(&prevent_default, params.url));
+  if (prevent_default)
+    return nullptr;
+
   content::NavigationController::LoadURLParams load_url_params(params.url);
   load_url_params.referrer = params.referrer;
   load_url_params.transition_type = params.transition;

atom/browser/native_window_observer.h

@@ -27,6 +27,9 @@ class NativeWindowObserver {
                                      const std::string& partition_id,
                                      WindowOpenDisposition disposition) {}
 
+  // Called when user is starting an navigation in web page.
+  virtual void WillNavigate(bool* prevent_default, const GURL& url) {}
+
   // Called when the window is gonna closed.
   virtual void WillCloseWindow(bool* prevent_default) {}
 

docs/api/browser-window.md

@@ -616,6 +616,19 @@ will be returned to `window.open` to let you have limited control of it.
 
 Calling `event.preventDefault()` can prevent creating new windows.
 
+### Event: 'will-naviagte'
+
+* `event` Event
+* `url` String
+
+Emitted when user or the page wants to start an navigation, it can happen when
+`window.location` object is changed or user clicks a link in the page.
+
+This event will not emit when the navigation is started programmely with APIs
+like `WebContents.loadUrl` and `WebContents.back`.
+
+Calling `event.preventDefault()` can prevent the navigation.
+
 ### Event: 'crashed'
 
 Emitted when the renderer process is crashed.

spec/api-browser-window-spec.coffee

@@ -208,3 +208,11 @@ describe 'browser-window module', ->
       w.once 'minimize', -> done()
       w.show()
       w.minimize()
+
+  describe 'will-navigate event', ->
+    it 'emits when user starts a navigation', (done) ->
+      w.webContents.on 'will-navigate', (event, url) ->
+        event.preventDefault()
+        assert.equal url, 'https://www.github.com/'
+        done()
+      w.loadUrl "file://#{fixtures}/pages/will-navigate.html"

spec/fixtures/pages/will-navigate.html

@@ -0,0 +1,7 @@
+<html>
+<body>
+<script type="text/javascript" charset="utf-8">
+  location = 'https://www.github.com'
+</script>
+</body>
+</html>