Modifying element attributes with JS in Selenium Python - Framework Patterns

Framework Mode - Modifying element attributes with JS

Folder Structure

selenium-python-project/
├── src/
│   ├── pages/
│   │   └── example_page.py
│   ├── tests/
│   │   └── test_modify_attributes.py
│   ├── utils/
│   │   └── js_executor.py
│   └── config/
│       └── config.py
├── requirements.txt
└── pytest.ini
    

Test Framework Layers

• Driver Layer: Manages Selenium WebDriver setup and teardown (in test setup fixtures).
• Page Objects: Classes representing web pages, with methods to interact with elements, including methods that use JavaScript to modify attributes.
• Tests: Test cases that use page objects to perform actions and assertions.
• Utilities: Helper functions like a JavaScript executor utility to run JS code on elements.
• Configuration: Settings for browser type, URLs, and credentials.

Configuration Patterns

Use a config.py file to store environment variables such as base URL, browser choice, and credentials.

Example:

# config/config.py
BASE_URL = "https://example.com"
BROWSER = "chrome"
USERNAME = "user"
PASSWORD = "pass"
    

Use pytest command line options or environment variables to switch browsers or environments dynamically.

Test Reporting and CI/CD Integration

• Use pytest with plugins like pytest-html or allure-pytest for readable HTML reports.
• Integrate tests into CI/CD pipelines (GitHub Actions, Jenkins) to run tests on code push.
• Reports show pass/fail status and screenshots on failure.

Best Practices

• Use Page Object Model: Keep JS attribute modification inside page object methods for reuse and clarity.
• Explicit Waits: Wait for elements to be present before modifying attributes to avoid errors.
• JavaScript Execution Utility: Centralize JS execution in a utility function to handle errors and logging.
• Keep Tests Clean: Tests should call page object methods, not raw JS code.
• Use Config for Flexibility: Control browser and environment settings without changing code.

Self Check

Where in this folder structure would you add a new method to change the disabled attribute of a button using JavaScript?

Key Result

Use Page Object Model with a JavaScript utility to modify element attributes cleanly and maintainably.

Practice

1. What does the following Selenium Python code do?
driver.execute_script("arguments[0].setAttribute('disabled', 'true')", element)

easy

A. It changes the element's text to 'true'.

B. It enables the web element by removing the 'disabled' attribute.

C. It disables the web element by setting its 'disabled' attribute to true.

D. It deletes the element from the page.

Solution

1. Step 1: Understand the JavaScript command

   The JavaScript code uses setAttribute to add or change the 'disabled' attribute of the element to 'true'.

2. Step 2: Effect on the web element

   Setting 'disabled' to 'true' makes the element disabled, meaning user interaction is blocked.

3. Final Answer:

   It disables the web element by setting its 'disabled' attribute to true. -> Option C

4. Quick Check:

   setAttribute('disabled', 'true') disables element [OK]

Hint: setAttribute('disabled', 'true') disables element [OK]

Common Mistakes:

• Confusing 'disabled' attribute with changing text content
• Thinking it removes the element
• Assuming it enables the element instead

2. Which of the following is the correct syntax to change an element's attribute 'class' to 'active' using Selenium Python's execute_script?

easy

A. driver.execute_script("arguments[0].setAttribute('class', 'active')", element)

B. driver.execute_script("element.setAttribute('class', 'active')")

C. driver.execute_script("arguments.setAttribute('class', 'active')", element)

D. driver.execute_script("arguments[0].setAttribute('class' = 'active')", element)

Solution

1. Step 1: Identify correct use of arguments in execute_script

   In Selenium, arguments[0] refers to the first argument passed after the script string, which is the element.

2. Step 2: Check JavaScript syntax for setAttribute

   The correct syntax is setAttribute('attributeName', 'value'). driver.execute_script("arguments[0].setAttribute('class', 'active')", element) uses this correctly with arguments[0].

3. Final Answer:

   driver.execute_script("arguments[0].setAttribute('class', 'active')", element) -> Option A

4. Quick Check:

   Use arguments[0].setAttribute('class', 'active') [OK]

Hint: Use arguments[0] for element in execute_script [OK]

Common Mistakes:

• Using 'element' directly inside the script string
• Wrong JavaScript syntax like '=' inside setAttribute
• Using 'arguments' without index

3. What will be the output of the following code snippet?

element = driver.find_element(By.ID, 'submit-btn')
driver.execute_script("arguments[0].setAttribute('data-test', 'passed')", element)
attr_value = element.get_attribute('data-test')
print(attr_value)

medium

A. SyntaxError

B. data-test

C. None

D. passed

Solution

1. Step 1: Modify attribute using JavaScript

   The script sets the 'data-test' attribute of the element to 'passed'.

2. Step 2: Retrieve the attribute value

   Calling get_attribute('data-test') fetches the updated value, which is 'passed'.

3. Final Answer:

   passed -> Option D

4. Quick Check:

   setAttribute then get_attribute returns new value [OK]

Hint: get_attribute returns updated attribute after JS change [OK]

Common Mistakes:

• Expecting None because attribute was not originally present
• Confusing attribute name with value
• Thinking JavaScript changes don't reflect in Selenium

4. Identify the error in the following code snippet that tries to change an element's 'title' attribute:

element = driver.find_element(By.CSS_SELECTOR, '.btn')
driver.execute_script("arguments[0].setAttribute('title', title)", element)

medium

A. The variable 'title' is not defined in the JavaScript context.

B. The element locator is incorrect.

C. The setAttribute method is misspelled.

D. execute_script cannot modify attributes.

Solution

1. Step 1: Analyze JavaScript string in execute_script

   The script uses 'title' as a variable inside the string, but it is not defined in JavaScript context.

2. Step 2: Understand variable passing in execute_script

   To pass a Python variable, it must be included as an argument and referenced via arguments[1] or similar.

3. Final Answer:

   The variable 'title' is not defined in the JavaScript context. -> Option A

4. Quick Check:

   JS variables must be passed explicitly [OK]

Hint: Pass variables as arguments, not inline strings [OK]

Common Mistakes:

• Using Python variables directly inside JS string
• Ignoring need for arguments[n] in execute_script
• Assuming locator error without checking script

5. You want to toggle a checkbox's 'checked' attribute using Selenium Python and JavaScript. Which code snippet correctly toggles the checkbox state?

hard

A. driver.execute_script("arguments[0].setAttribute('checked', !arguments[0].checked)", checkbox_element)

B. driver.execute_script("arguments[0].checked = !arguments[0].checked", checkbox_element)

C. driver.execute_script("arguments[0].checked = 'false'", checkbox_element)

D. driver.execute_script("arguments[0].removeAttribute('checked')", checkbox_element)

Solution

1. Step 1: Understand checkbox 'checked' property vs attribute

   The 'checked' property is a boolean that controls checkbox state; toggling it flips the state.

2. Step 2: Evaluate each option's effect

   driver.execute_script("arguments[0].checked = !arguments[0].checked", checkbox_element) uses JavaScript to toggle the boolean property correctly. driver.execute_script("arguments[0].setAttribute('checked', !arguments[0].checked)", checkbox_element) tries to set attribute with a boolean, which converts to string and may not work as expected. driver.execute_script("arguments[0].checked = 'false'", checkbox_element) sets 'checked' to string 'false', which does not uncheck. driver.execute_script("arguments[0].removeAttribute('checked')", checkbox_element) removes 'checked' attribute but does not toggle back on.

3. Final Answer:

   driver.execute_script("arguments[0].checked = !arguments[0].checked", checkbox_element) -> Option B

4. Quick Check:

   Toggle boolean property 'checked' to flip checkbox [OK]

Hint: Toggle checkbox by flipping 'checked' boolean property [OK]

Common Mistakes:

• Using setAttribute with boolean values
• Setting 'checked' to string 'false' instead of boolean
• Removing attribute without toggling back