Selenium: WebDriver, Locators, Waits, Actions and Grid Reference Guide

# Python — Selenium 4 (W3C WebDriver)
pip install "selenium>=4.15"
# Drivers are auto-managed by Selenium Manager — no chromedriver download needed

# Java — Maven
# 
#   org.seleniumhq.selenium
#   selenium-java
#   4.20.0
# 

# Node / TS
npm install selenium-webdriver

# Selenium Grid — multi-node parallel runner (Docker)
docker network create grid
docker run -d -p 4442-4444:4442-4444 --net grid --name selenium-hub selenium/hub:4
docker run -d --net grid -e SE_EVENT_BUS_HOST=selenium-hub selenium/node-chrome:4
docker run -d --net grid -e SE_EVENT_BUS_HOST=selenium-hub selenium/node-firefox:4
# Console → http://localhost:4444/grid/console

# Standalone (single node + hub in one container)
docker run -d -p 4444:4444 --shm-size=2g selenium/standalone-chrome:4

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException

driver = webdriver.Chrome()
wait = WebDriverWait(driver, timeout=10, poll_frequency=0.25,
                     ignored_exceptions=[TimeoutException])

# Explicit wait — most common pattern. Always prefer over time.sleep().
btn = wait.until(EC.element_to_be_clickable((By.CSS_SELECTOR, "button#pay")))
btn.click()

# Custom condition — any callable that returns truthy when ready
def text_in(locator, fragment):
    def _predicate(d):
        return fragment in d.find_element(*locator).text
    return _predicate

wait.until(text_in((By.ID, "status"), "Paid"))

# Fluent-wait shorthand — same WebDriverWait, just chained
WebDriverWait(driver, 5).until(EC.url_contains("/checkout/success"))

# Implicit wait — driver-wide default. Don't mix with explicit waits.
driver.implicitly_wait(0)        # 0 = off — recommended

# Never do this — flaky and slow:
# import time; time.sleep(5)

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.common.action_chains import ActionChains

driver = webdriver.Chrome()
driver.get("https://example.com/canvas")

src = driver.find_element(By.ID, "tile")
dst = driver.find_element(By.ID, "slot")

# Drag-and-drop via low-level actions
ActionChains(driver)\
    .move_to_element(src)\
    .click_and_hold()\
    .pause(0.2)\
    .move_to_element(dst)\
    .release()\
    .perform()

# Right-click context menu
ActionChains(driver).context_click(src).perform()

# Keyboard shortcut
ActionChains(driver).key_down(Keys.CONTROL).send_keys('s').key_up(Keys.CONTROL).perform()

# Hover, then click a tooltip that appears
ActionChains(driver).move_to_element(src).pause(0.1).perform()
driver.find_element(By.CSS_SELECTOR, ".tooltip-action").click()

# Scroll into view (Selenium 4 native scroll origin)
ActionChains(driver).scroll_to_element(dst).perform()
ActionChains(driver).scroll_by_amount(0, 500).perform()

# End-to-end Selenium 4 — headless Chrome, explicit waits, Page Object lite.
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

def make_driver():
    opts = Options()
    opts.add_argument("--headless=new")
    opts.add_argument("--window-size=1280,800")
    return webdriver.Chrome(options=opts)              # Selenium Manager picks the driver

class LoginPage:
    URL = "https://example.com/login"

    def __init__(self, driver):
        self.d, self.wait = driver, WebDriverWait(driver, 10)

    def open(self):
        self.d.get(self.URL); return self

    def login(self, user, pw):
        self.d.find_element(By.ID, "email").send_keys(user)
        self.d.find_element(By.ID, "password").send_keys(pw)
        self.d.find_element(By.CSS_SELECTOR, "button[type=submit]").click()
        self.wait.until(EC.url_contains("/dashboard"))
        return self

def test_login():
    d = make_driver()
    try:
        LoginPage(d).open().login("ana@x.com", "secret")
        assert "Welcome" in d.find_element(By.TAG_NAME, "h1").text
    finally:
        d.quit()                                       # always close — orphan procs leak

if __name__ == "__main__":
    test_login()