Selenium WebDriver Fundamentals Questions

public class LoginPage {
    private WebDriver driver;
    private WebDriverWait wait;

    // private locators
    private By usernameInput = By.id("username");
    private By passwordInput = By.id("password");
    private By loginButton   = By.cssSelector("button[type='submit']");
    private By errorMessage  = By.cssSelector(".login-error");

    // constructor
    public LoginPage(WebDriver driver) {
        this.driver = driver;
        this.wait = new WebDriverWait(driver, Duration.ofSeconds(10));
        waitUntilLoaded();
    }

    // wait until page loaded (explicit wait)
    public void waitUntilLoaded() {
        // wait for username input to be visible and enabled
        wait.until(ExpectedConditions.visibilityOfElementLocated(usernameInput));
        wait.until(ExpectedConditions.elementToBeClickable(loginButton));
    }

    // perform login and return next page object
    public HomePage login(String username, String password) {
        WebElement u = wait.until(ExpectedConditions.elementToBeClickable(usernameInput));
        u.clear();
        u.sendKeys(username);

        WebElement p = driver.findElement(passwordInput);
        p.clear();
        p.sendKeys(password);

        driver.findElement(loginButton).click();

        // optionally wait for indicator on HomePage before returning
        return new HomePage(driver);
    }

    // check if error is visible
    public boolean isErrorVisible() {
        try {
            return wait.until(ExpectedConditions.visibilityOfElementLocated(errorMessage)) != null;
        } catch (TimeoutException e) {
            return false;
        }
    }
}

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException, StaleElementReferenceException

def click_when_clickable(driver, locator, timeout=10, retries=1, poll_frequency=0.5):
    """
    Wait until element located by `locator` is clickable, then click.
    Raises TimeoutException with actionable message on failure.
    Optionally retries on StaleElementReferenceException up to `retries`.
    :param driver: Selenium WebDriver instance
    :param locator: tuple (By, selector)
    :param timeout: max seconds to wait each attempt
    :param retries: number of stale-element retries
    :param poll_frequency: polling interval for WebDriverWait
    """
    attempts = 0
    last_exc = None
    while attempts <= retries:
        try:
            wait = WebDriverWait(driver, timeout, poll_frequency=poll_frequency)
            element = wait.until(EC.element_to_be_clickable(locator))
            element.click()
            return
        except StaleElementReferenceException as e:
            last_exc = e
            attempts += 1
            # short backoff before retry
            continue
        except TimeoutException as e:
            message = f"Timed out after {timeout}s waiting for element {locator} to be clickable."
            raise TimeoutException(message) from e
    # if we exhausted retries for stale element
    raise StaleElementReferenceException(f"Element {locator} became stale after {retries} retries.") from last_exc

# Python/Selenium
el = driver.find_element(By.ID, "submit")
el.click()   # ensure locate just before action

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

el = WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.ID, "submit")))
el.click()

def click_with_retry(locator, attempts=3):
    for _ in range(attempts):
        try:
            driver.find_element(*locator).click()
            return
        except StaleElementReferenceException:
            time.sleep(0.5)
    raise