JavaScript executor basics in Selenium Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to execute JavaScript that returns the page title.

Selenium Python

title = driver.execute_script([1])

Drag options to blanks, or click blank then click option'

A"return document.title"

B"document.title"

C"return title"

D"document.getTitle()"

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the return keyword causes the result to be None.

Using incorrect JavaScript syntax like document.getTitle() which does not exist.

The JavaScript code must return the document title explicitly using return document.title for Selenium to capture it.

2fill in blank

medium

Complete the code to scroll the page down by 500 pixels using JavaScript executor.

Selenium Python

driver.execute_script([1])

Drag options to blanks, or click blank then click option'

A"window.scroll(500, 0)"

B"scrollTo(0, 500)"

C"scrollBy(500, 0)"

D"window.scrollBy(0, 500)"

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping x and y values causes horizontal scrolling instead of vertical.

Using scrollTo without window. prefix may cause errors.

The correct JavaScript to scroll vertically down by 500 pixels is window.scrollBy(0, 500).

3fill in blank

hard

Fix the error in the code to click an element using JavaScript executor.

Selenium Python

driver.execute_script("arguments[0].[1]();", element)

Drag options to blanks, or click blank then click option'

AclickElement

Bclick

CclickOn

Dclicker

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent method names causes JavaScript errors.

Misspelling the method name leads to runtime failures.

The correct JavaScript method to simulate a click is click(). Other options are invalid method names.

4fill in blank

hard

Fill both blanks to return the inner text of an element using JavaScript executor.

Selenium Python

text = driver.execute_script("return arguments[[1]].[2]", element)

Drag options to blanks, or click blank then click option'

A0

B1

CinnerText

DtextContent

Attempts:

3 left

💡 Hint

Common Mistakes

Using argument index 1 causes undefined errors.

Using incorrect property names causes empty or undefined results.

The first argument index is 0 because element is the first argument. To get visible text, textContent is a reliable property.

5fill in blank

hard

Fill all three blanks to set the value of an input element using JavaScript executor.

Selenium Python

driver.execute_script("arguments[[1]].[2] = arguments[[3]]", input_element, value)

Drag options to blanks, or click blank then click option'

A0

B1

Cvalue

D"value"

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up argument indexes causes errors or no effect.

Using string literal "value" instead of variable causes wrong assignment.

The input element is the first argument (index 0), so use arguments[0]. The property to set is value. The value to assign is the second argument (index 1), so arguments[1].

Practice

1. What is the main purpose of using execute_script in Selenium with Python?

easy

A. To run JavaScript code inside the browser during a test

B. To start the Selenium WebDriver server

C. To locate elements using CSS selectors

D. To take screenshots of the browser window

Solution

1. Step 1: Understand the role of execute_script

   This method allows running JavaScript code inside the browser from Selenium tests.

2. Step 2: Compare with other Selenium functions

   Other functions locate elements or control the browser, but execute_script specifically runs JS code.

3. Final Answer:

   To run JavaScript code inside the browser during a test -> Option A

4. Quick Check:

   execute_script runs JS code [OK]

Hint: Remember: execute_script runs JS code inside browser [OK]

Common Mistakes:

• Confusing execute_script with element locating methods
• Thinking execute_script starts WebDriver server
• Assuming execute_script takes screenshots

2. Which of the following is the correct syntax to run JavaScript code that returns the page title using Selenium's execute_script in Python?

easy

A. driver.execute_script('return document.title')

B. driver.execute_script(document.title)

C. driver.execute_script('document.title')

D. driver.execute_script(return document.title)

Solution

1. Step 1: Check correct string usage for JS code

   The JavaScript code must be passed as a string, so quotes are needed around 'return document.title'.

2. Step 2: Verify the return keyword usage

   To get a value back from JS, 'return' must be used inside the string.

3. Final Answer:

   driver.execute_script('return document.title') -> Option A

4. Quick Check:

   JS code as string with return keyword [OK]

Hint: Always pass JS code as a quoted string with return [OK]

Common Mistakes:

• Passing JS code without quotes
• Omitting the return keyword when expecting a value
• Using invalid syntax without quotes or return

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

title = driver.execute_script('return document.title')
print(title)

medium

A. Prints the WebDriver object reference

B. Prints None because execute_script returns nothing

C. Prints the current page's title as a string

D. Raises a syntax error due to missing quotes

Solution

1. Step 1: Understand what execute_script returns

   When JavaScript code returns a value, execute_script returns it to Python.

2. Step 2: Analyze the JS code 'return document.title'

   This returns the page title as a string, so the variable 'title' holds that string.

3. Final Answer:

   Prints the current page's title as a string -> Option C

4. Quick Check:

   execute_script returns JS value [OK]

Hint: Return keyword in JS returns value to Python [OK]

Common Mistakes:

• Assuming execute_script returns None always
• Confusing JS code string syntax
• Expecting execute_script to print automatically

4. Identify the error in this code snippet:

driver.execute_script(return document.body.style.backgroundColor = 'red')

medium

A. Incorrect method name, should be execute_js

B. Missing quotes around the JavaScript code string

C. Cannot change background color with JavaScript

D. Syntax error due to missing parentheses

Solution

1. Step 1: Check the argument passed to execute_script

   The JavaScript code must be passed as a string, but here it is passed without quotes.

2. Step 2: Confirm method name and JS validity

   The method name is correct and changing background color with JS is valid.

3. Final Answer:

   Missing quotes around the JavaScript code string -> Option B

4. Quick Check:

   JS code must be a quoted string [OK]

Hint: Always wrap JS code in quotes for execute_script [OK]

Common Mistakes:

• Forgetting quotes around JS code
• Thinking method name is wrong
• Believing JS cannot change styles

5. You want to scroll the page down by 500 pixels using Selenium's JavaScript executor in Python. Which code snippet correctly does this?

hard

A. driver.execute_script('window.scrollTo(500, 0)')

B. driver.execute_script('scrollTo(0, 500)')

C. driver.execute_script('scrollBy(500, 0)')

D. driver.execute_script('window.scrollBy(0, 500)')

Solution

1. Step 1: Understand scrolling methods in JavaScript

   window.scrollBy(x, y) scrolls by x and y pixels relative to current position.

2. Step 2: Identify correct parameters for scrolling down

   To scroll down 500 pixels, x=0 and y=500 is correct.

3. Final Answer:

   driver.execute_script('window.scrollBy(0, 500)') -> Option D

4. Quick Check:

   scrollBy(0, 500) scrolls down 500px [OK]

Hint: Use window.scrollBy(0, pixels) to scroll down [OK]

Common Mistakes:

• Swapping x and y values
• Using scrollTo instead of scrollBy incorrectly
• Passing wrong parameters causing horizontal scroll