How to check if an alert exists using WebDriver?

Question

I need to check the existence of Alert in WebDriver.

Sometimes it pops up an alert but sometimes it will not pop up. I need to check if the alert exists first, then

Answer 1

I found catching exception of driver.switchTo().alert(); is so slow in Firefox (FF V20 & selenium-java-2.32.0).`

So I choose another way:

    private static boolean isDialogPresent(WebDriver driver) {
        try {
            driver.getTitle();
            return false;
        } catch (UnhandledAlertException e) {
            // Modal dialog showed
            return true;
        }
    }

And it's a better way when most of your test cases is NO dialog present (throwing exception is expensive).