How to Handle Alerts in webpage

What is a JavaScript Alert?

Alerts are native browser popups (alert, confirm, or prompt boxes) that WebDriver cannot interact with using normal element locators — they require the dedicated Alert interface.

Handling an Alert

Alert alert = driver.switchTo().alert();
String text = alert.getText();
alert.accept();  // clicks OK
alert.dismiss(); // clicks Cancel
alert.sendKeys("input text"); // for prompt boxes

Why This Matters

Attempting to interact with the page before handling an open alert will throw an exception, so alerts must always be switched to and resolved first.