Selenium Wait Commands – Implicit Waits and Explicit Waits

Selenium Python is one of the great tools for testing automation. These days most of the web apps are using AJAX techniques. When a page is loaded by the browser, the elements within that page may load at different time intervals. This makes locating elements difficult: if an element is not yet present in the DOM, a locate function will raise an ElementNotVisibleException exception. Using waits, we can solve this issue. Waiting provides some slack between actions performed – mostly locating an element or any other operation with the element. Selenium WebDriver provides two types of waits –

• Implicit Waits
• Explicit Waits

Implicit Waits

An implicit wait tells WebDriver to poll the DOM for a certain amount of time when trying to find any element (or elements) not immediately available. The default setting is 0. Once set, the implicit wait is set for the life of the WebDriver object. Let’s consider an example –

Python3

# import webdriver
from selenium import webdriver

driver = webdriver.Firefox()

# set implicit wait time
driver.implicitly_wait(10) # seconds

# get url
driver.get("http://somedomain / url_that_delays_loading")

# get element after 10 seconds
myDynamicElement = driver.find_element_by_id("myDynamicElement")

This waits up to 10 seconds before throwing a Timeout Exception unless it finds the element to return within 10 seconds. To check out how to practically implement Implicit Waits in WebDriver, checkout.

Implicit waits in Selenium Python

Explicit Waits

An explicit wait is a code you define to wait for a certain condition to occur before proceeding further in the code. The extreme case of this is time.sleep(), which sets the condition to an exact time period to wait. There are some convenience methods provided that help you write code that will wait only as long as required. Explicit waits are achieved by using webdriverWait class in combination with expected_conditions. Let’s consider an example –

Python3

# import necessary classes
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

# create driver object
driver = webdriver.Firefox()

# A URL that delays loading
driver.get("http://somedomain / url_that_delays_loading")

try:
    # wait 10 seconds before looking for element
    element = WebDriverWait(driver, 10).until(
        EC.presence_of_element_located((By.ID, "myDynamicElement"))
    )
finally:
    # else quit
    driver.quit()

This waits up to 10 seconds before throwing a TimeoutException unless it finds the element to return within 10 seconds. WebDriverWait by default calls the ExpectedCondition every 500 milliseconds until it returns successfully.

Expected Conditions –

There are some common conditions that are frequently of use when automating web browsers. For example, presence_of_element_located, title_is, ad so on. One can check entire methods from here –

Convenience Methods

. Some of them are –

• title_is
• title_contains
• presence_of_element_located
• visibility_of_element_located
• visibility_of
• presence_of_all_elements_located
• element_located_to_be_selected
• element_selection_state_to_be
• element_located_selection_state_to_be
• alert_is_present

To check out how to practically implement Implicit Waits in WebDriver, checkout

Explicit waits in Selenium Python