CSS selector syntax in Selenium Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a CSS selector?

A CSS selector is a pattern used to select and style HTML elements on a web page.

beginner

How do you select an element by its ID using CSS selector syntax?

Use the hash symbol (#) followed by the element's ID. Example: #header selects the element with id="header".

beginner

How do you select elements by their class name in CSS selectors?

Use a dot (.) followed by the class name. Example: <code>.button</code> selects all elements with class="button".

intermediate

What does the CSS selector div > p select?

It selects all <p> elements that are direct children of a <div> element.

beginner

How do you select all elements of a certain type, for example all paragraphs?

Use the element name as the selector. Example: p selects all <p> elements.

Which CSS selector selects elements with class 'active'?

A .active

B #active

C *active

D active

The dot (.) is used to select elements by class name.

What does the selector ul li select?

A All <ul> elements inside <li>

B Only direct child <li> elements of <ul>

C All <li> elements anywhere

D All <li> elements inside any <ul>

A space between selectors means any descendant, so all

inside

.

How do you select an element with id 'main'?

A #main

B .main

C main

D *main

The hash (#) selects elements by their id attribute.

What does the selector input[type='text'] select?

A All elements with attribute type

B All input elements

C All input elements with type attribute equal to 'text'

D All text elements

Attribute selectors select elements with specific attribute values.

Which selector selects all direct children <p> of a <div>?

A div p

B div > p

C div + p

D div ~ p

The > symbol selects direct children only.

Explain how to select elements by ID, class, and element type using CSS selectors.

Think about the symbols used before the name.

Describe the difference between the selectors div p and div > p.

Look at the space vs > symbol.

Practice

1. Which CSS selector syntax correctly selects an element with the id submitBtn?

easy

A. #submitBtn

B. .submitBtn

C. submitBtn

D. *submitBtn

Solution

1. Step 1: Understand CSS id selector syntax

   In CSS, the # symbol is used to select elements by their id attribute.

2. Step 2: Match the selector to the id

   The selector #submitBtn targets the element with id="submitBtn" exactly.

3. Final Answer:

   #submitBtn -> Option A

4. Quick Check:

   Id selector uses # = #submitBtn [OK]

Hint: Use # before id names to select by id [OK]

Common Mistakes:

• Using . instead of # for id
• Omitting # and using just the id name
• Using * which selects all elements

2. Which of the following is the correct CSS selector to select all elements with the class active?

easy

A. #active

B. *active

C. .active

D. active

Solution

1. Step 1: Recall CSS class selector syntax

   Classes are selected using a dot . followed by the class name.

2. Step 2: Identify the correct selector

   The selector .active selects all elements with class="active".

3. Final Answer:

   .active -> Option C

4. Quick Check:

   Class selector uses . = .active [OK]

Hint: Use . before class names to select by class [OK]

Common Mistakes:

• Using # instead of . for class
• Omitting . and using just class name
• Using * which selects all elements

3. Given the HTML snippet:

<input type="text" name="username" class="input-field" id="user" />

Which CSS selector will select this input element by its attribute name?

medium

A. input[name='username']

B. input#username

C. input.class='input-field'

D. input[name=username]

Solution

1. Step 1: Understand attribute selector syntax

   To select elements by attribute, use square brackets with attribute and value: [attr='value'].

2. Step 2: Match the selector to the input element

   input[name='username'] selects input elements with name="username" exactly.

3. Final Answer:

   input[name='username'] -> Option A

4. Quick Check:

   Attribute selector uses [attr='value'] = input[name='username'] [OK]

Hint: Use [attr='value'] to select by attribute [OK]

Common Mistakes:

• Missing quotes around attribute value
• Using # for attribute instead of []
• Incorrect syntax like input.class='input-field'

4. Identify the error in this CSS selector used in Selenium:
driver.findElement(By.cssSelector("div#main .content > p:first-child"));
What is wrong with this selector?

medium

A. The pseudo-class ':first-child' is not supported in CSS selectors.

B. The space between 'div#main' and '.content' is incorrect.

C. The '>' combinator cannot be used with classes.

D. The selector syntax is correct and will work as expected.

Solution

1. Step 1: Analyze the selector components

   The selector targets a p element that is the first child inside an element with class content, which is inside a div with id main.

2. Step 2: Check CSS selector validity in Selenium

   All parts including #main, .content, child combinator >, and pseudo-class :first-child are valid CSS selectors supported by Selenium.

3. Final Answer:

   The selector syntax is correct and will work as expected. -> Option D

4. Quick Check:

   Valid CSS selector syntax = correct [OK]

Hint: Check if selector uses valid CSS syntax supported by Selenium [OK]

Common Mistakes:

• Assuming pseudo-classes like :first-child are unsupported
• Misunderstanding combinator usage
• Thinking spaces between selectors are always wrong

5. You want to select all button elements that have both the class btn and an attribute data-action equal to save. Which CSS selector is correct?

hard

A. button#btn[data-action=save]

B. button.btn[data-action='save']

C. button .btn[data-action='save']

D. button.btn[data-action=save]

Solution

1. Step 1: Combine class and attribute selectors correctly

   To select elements with a class and attribute, chain selectors without spaces: button.btn[data-action='save'].

2. Step 2: Verify syntax details

   Quotes around attribute value are recommended for exact matching; no spaces between element, class, and attribute selectors.

3. Final Answer:

   button.btn[data-action='save'] -> Option B

4. Quick Check:

   Combine selectors without spaces = button.btn[data-action='save'] [OK]

Hint: Chain selectors without spaces; quote attribute values [OK]

Common Mistakes:

• Using spaces between element and class selectors
• Omitting quotes around attribute values
• Using # instead of . for class