How to handle Windows and Frames in WebDriver?

It's rare for a modern web application not to have any frames or to be constrained to a single window. WebDriver supports moving between named windows using the "switchTo" method:

driver.switchTo ().window ("windowName");

All calls to driver will now be interpreted as being directed to the particular window. But how do you know the window's name? Take a look at the javascript or link that opened it:

<a href="somewhere.html" target="windowName">Click here to open a new window</a>

Alternatively, you can pass a "window handle" to the "switchTo().window()" method. Knowing this, it's possible to iterate over every open window like so:

for (String handle : driver.getWindowHandles()) {
  driver.switchTo().window(handle);
}

You can also swing from frame to frame (or into iframes):

driver.switchTo().frame("frameName");

It's possible to access subframes by chaining switchTo() calls, and you can specify the frame by its index too. That is:

driver.switchTo().frame("frameName")
      .switchTo().frame(0)
      .switchTo().frame("child");

would go to the frame named "child" of the first subframe of the frame called "frameName". All frames are evaluated as if from currently switched to frame. To get back to the top level, call:

driver.switchTo().defaultContent();