findElement by cssSelector in Selenium Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does findElement(By.cssSelector()) do in Selenium?

It locates the first web element on the page that matches the given CSS selector string.

beginner

Write a CSS selector to find an element with class btn-primary.

Use <code>".btn-primary"</code> as the CSS selector. The dot <code>.</code> means class in CSS selectors.

beginner

How do you find an element with id login using CSS selector?

Use "#login" as the CSS selector. The hash # means id in CSS selectors.

intermediate

What is the difference between findElement and findElements?

findElement returns the first matching element or throws an exception if none found. findElements returns a list of all matching elements or an empty list if none found.

intermediate

Why is using CSS selectors often preferred over XPath in Selenium?

CSS selectors are usually faster and simpler to write. They are well supported by browsers and easier to read for many common cases.

Which CSS selector finds all elements with class 'active'?

A "#active"

B "active"

C ".active"

D "*active"

The dot (.) before 'active' selects elements by class name.

What does the CSS selector '#submitBtn' select?

A Elements with id 'submitBtn'

B Elements with name 'submitBtn'

C All buttons

D Elements with class 'submitBtn'

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

What happens if findElement(By.cssSelector()) finds no matching element?

A Throws NoSuchElementException

B Returns an empty list

C Returns null

D Returns a default element

findElement throws NoSuchElementException if no element matches.

Which CSS selector finds all input elements inside a form?

A "form > input"

B "form input"

C "input form"

D "form + input"

"form input" selects all input elements inside any form, at any depth.

Which is a valid CSS selector to find a button with both classes 'btn' and 'primary'?

A ".btn#primary"

B "#btn.primary"

C "btn.primary"

D ".btn.primary"

Multiple classes are chained with dots: .btn.primary means element with both classes.

Explain how to use findElement(By.cssSelector()) to locate a web element by class and id.

Think about how CSS selectors identify elements by id and class.

Describe the difference between findElement and findElements when using CSS selectors in Selenium.

Consider what happens if no elements match.

Practice

1. What does driver.findElement(By.cssSelector(".btn-primary")) do in Selenium Java?

easy

A. Finds all elements with class 'btn-primary' on the page

B. Finds the first element with class 'btn-primary' on the page

C. Finds the element with id 'btn-primary'

D. Throws an error if any element has class 'btn-primary'

Solution

1. Step 1: Understand the method used

   findElement returns the first matching element found on the page.

2. Step 2: Analyze the CSS selector

   The selector .btn-primary matches elements with class btn-primary.

3. Final Answer:

   Finds the first element with class 'btn-primary' on the page -> Option B

4. Quick Check:

   findElement + .class = first matching element [OK]

Hint: findElement + .class finds first element with that class [OK]

Common Mistakes:

• Confusing findElement with findElements
• Using id selector syntax for class
• Thinking it finds all matching elements

2. Which of the following is the correct syntax to find an element with id 'login' using CSS selector in Selenium Java?

easy

A. driver.findElement(By.cssSelector(".login"));

B. driver.findElement(By.cssSelector("*login"));

C. driver.findElement(By.cssSelector("login"));

D. driver.findElement(By.cssSelector("#login"));

Solution

1. Step 1: Identify CSS selector for id

   In CSS, id selectors start with #, so #login selects element with id 'login'.

2. Step 2: Check syntax correctness

   The syntax driver.findElement(By.cssSelector("#login")); is correct for Selenium Java.

3. Final Answer:

   driver.findElement(By.cssSelector("#login")); -> Option D

4. Quick Check:

   Id selector uses # [OK]

Hint: Use # for id selectors in CSS [OK]

Common Mistakes:

• Using . instead of # for id
• Missing quotes around selector
• Using invalid selector syntax

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

WebElement element = driver.findElement(By.cssSelector("div.content > p.highlight"));
String text = element.getText();
System.out.println(text);

Assuming the HTML is:

<div class="content">
  <p class="highlight">Hello</p>
  <p>World</p>
</div>

medium

A. HelloWorld

B. World

C. Hello

D. NoSuchElementException

Solution

1. Step 1: Understand the CSS selector used

   div.content > p.highlight selects a p element with class highlight that is a direct child of div with class content.

2. Step 2: Match selector to HTML

   The first p inside div.content has class highlight and text "Hello".

3. Final Answer:

   Hello -> Option C

4. Quick Check:

   Selector matches first p.highlight text [OK]

Hint: Use > for direct child in CSS selectors [OK]

Common Mistakes:

• Ignoring direct child combinator >
• Selecting wrong paragraph text
• Assuming all p tags are selected

4. Identify the error in this Selenium Java code:

WebElement button = driver.findElement(By.cssSelector("button#submit-btn.active"));
button.click();

Given the HTML:

<button id="submit-btn">Submit</button>

medium

A. CSS selector requires both id and class but element has no class 'active'

B. Syntax error in findElement method call

C. button.click() is invalid method

D. NoSuchElementException because id selector is wrong

Solution

1. Step 1: Analyze the CSS selector

   The selector button#submit-btn.active looks for a button with id submit-btn AND class active.

2. Step 2: Compare with HTML element

   The button has id submit-btn but no class active, so selector matches no element.

3. Final Answer:

   CSS selector requires both id and class but element has no class 'active' -> Option A

4. Quick Check:

   Selector requires all parts to match [OK]

Hint: All parts in CSS selector must match element attributes [OK]

Common Mistakes:

• Assuming partial match works in CSS selector
• Ignoring missing class in element
• Thinking click() method is invalid

5. You want to find the first input element inside a form with class 'search' that is enabled and visible. Which CSS selector is best to use with findElement in Selenium Java?

hard

A. form.search input:not([disabled])

B. form.search > input[disabled='false']

C. form.search input:enabled

D. form.search input[visible='true']

Solution

1. Step 1: Understand CSS selectors for enabled inputs

   CSS does not have a standard :enabled pseudo-class for all browsers; instead, :not([disabled]) selects inputs without the disabled attribute.

2. Step 2: Check options for correctness

   form.search input:enabled uses :enabled which is not widely supported in CSS selectors for Selenium.
   form.search > input[disabled='false'] uses attribute [disabled='false'] which is invalid because disabled is boolean attribute.
   form.search input:not([disabled]) uses :not([disabled]) which correctly selects enabled inputs.
   form.search input[visible='true'] uses [visible='true'] which is not a valid attribute for visibility.

3. Final Answer:

   form.search input:not([disabled]) -> Option A

4. Quick Check:

   Use :not([disabled]) to find enabled inputs [OK]

Hint: Use :not([disabled]) to select enabled inputs [OK]

Common Mistakes:

• Using unsupported :enabled pseudo-class
• Checking disabled='false' attribute incorrectly
• Using non-existent visible attribute