[selenium] How to check if an alert exists using WebDriver?

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 I can accept or dismiss it or it will say: no alert found.

The following (C# implementation, but similar in Java) allows you to determine if there is an alert without exceptions and without creating the WebDriverWait object.

boolean isDialogPresent(WebDriver driver) {
    IAlert alert = ExpectedConditions.AlertIsPresent().Invoke(driver);
    return (alert != null);
}

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).

I would suggest to use ExpectedConditions and alertIsPresent(). ExpectedConditions is a wrapper class that implements useful conditions defined in ExpectedCondition interface.

WebDriverWait wait = new WebDriverWait(driver, 300 /*timeout in seconds*/);
if(wait.until(ExpectedConditions.alertIsPresent())==null)
    System.out.println("alert was not present");
else
    System.out.println("alert was present");

ExpectedConditions is obsolete, so:

        WebDriverWait wait = new WebDriverWait(driver, TimeSpan.FromSeconds(15));
        wait.Until(SeleniumExtras.WaitHelpers.ExpectedConditions.AlertIsPresent());

C# Selenium 'ExpectedConditions is obsolete'

I would suggest to use ExpectedConditions and alertIsPresent(). ExpectedConditions is a wrapper class that implements useful conditions defined in ExpectedCondition interface.

public boolean isAlertPresent(){
    boolean foundAlert = false;
    WebDriverWait wait = new WebDriverWait(driver, 0 /*timeout in seconds*/);
    try {
        wait.until(ExpectedConditions.alertIsPresent());
        foundAlert = true;
    } catch (TimeoutException eTO) {
        foundAlert = false;
    }
    return foundAlert;
}

Note: this is based on the answer by nilesh, but adapted to catch the TimeoutException which is thrown by the wait.until() method.

This code will check whether the alert is present or not.

public static void isAlertPresent(){
    try{
    Alert alert = driver.switchTo().alert();
    System.out.println(alert.getText()+" Alert is Displayed"); 
    }
    catch(NoAlertPresentException ex){
    System.out.println("Alert is NOT Displayed");
    }
    }

public boolean isAlertPresent() 
{ 
    try 
    { 
        driver.switchTo().alert(); 
        return true; 
    }   // try 
    catch (NoAlertPresentException Ex) 
    { 
        return false; 
    }   // catch 
}   // isAlertPresent()

check the link here https://groups.google.com/forum/?fromgroups#!topic/webdriver/1GaSXFK76zY

public static void handleAlert(){
    if(isAlertPresent()){
        Alert alert = driver.switchTo().alert();
        System.out.println(alert.getText());
        alert.accept();
    }
}
public static boolean isAlertPresent(){
      try{
          driver.switchTo().alert();
          return true;
      }catch(NoAlertPresentException ex){
          return false;
      }
}

public boolean isAlertPresent() {

try 
{ 
    driver.switchTo().alert(); 
    system.out.println(" Alert Present");
}  
catch (NoAlertPresentException e) 
{ 
    system.out.println("No Alert Present");
}    

}