Why XPath functions (contains, starts-with) in Selenium Java? - Purpose & Use Cases

The Big Idea

Discover how a few smart XPath tricks can save you hours of tedious clicking!

The Scenario

Imagine you are testing a website with hundreds of buttons and links. You need to find a button that has a label starting with 'Submit' or contains the word 'Next'. Doing this by clicking and checking each element manually is like searching for a needle in a haystack.

The Problem

Manually checking each element is slow and tiring. You might miss some buttons or click the wrong ones. It's easy to make mistakes, and repeating this every time the page changes wastes a lot of time.

The Solution

XPath functions like contains() and starts-with() let you write smart queries to find elements by partial text or attributes. This means you can quickly and accurately select the right elements without checking each one manually.

Before vs After

✗ Before

driver.findElement(By.xpath("//button[text()='Submit Form']"));

✓ After

driver.findElement(By.xpath("//button[starts-with(text(),'Submit')]");
driver.findElement(By.xpath("//a[contains(text(),'Next')]");

What It Enables

With these XPath functions, you can easily find elements even if their text changes slightly, making your tests more flexible and reliable.

Real Life Example

On a shopping site, the 'Add to Cart' button might say 'Add to Cart Now' or 'Add to Cart - Limited Offer'. Using starts-with() or contains() helps your test find the button no matter the exact text.

Key Takeaways

Manual element search is slow and error-prone.

XPath functions contains() and starts-with() simplify locating elements by partial text.

These functions make tests more flexible and easier to maintain.

Practice

1. Which XPath function would you use to locate elements whose attribute contains a specific substring anywhere within it?

easy

A. starts-with()

B. ends-with()

C. contains()

D. equals()

Solution

1. Step 1: Understand the purpose of contains()

   The contains() function checks if an attribute or text contains a given substring anywhere inside it.

2. Step 2: Compare with other functions

   starts-with() checks only the beginning, ends-with() is not standard XPath 1.0, and equals() is not an XPath function.

3. Final Answer:

   contains() -> Option C

4. Quick Check:

   Substring anywhere = contains() [OK]

Hint: Use contains() for substring anywhere inside attribute [OK]

Common Mistakes:

• Confusing contains() with starts-with()
• Using ends-with() which is not standard XPath 1.0
• Trying to use equals() as XPath function

2. Which of the following is the correct XPath syntax to find a button element whose id attribute starts with "submit"?

easy

A. //button[contains(@id, 'submit')]

B. //button[@id*='submit']

C. //button[@id^='submit']

D. //button[starts-with(@id, 'submit')]

Solution

1. Step 1: Identify the correct XPath function for 'starts with'

   The function starts-with() is used to check if an attribute starts with a substring.

2. Step 2: Check syntax correctness

   //button[starts-with(@id, 'submit')] is correct XPath syntax. Options B and C use invalid XPath operators.

3. Final Answer:

   //button[starts-with(@id, 'submit')] -> Option D

4. Quick Check:

   Starts with = starts-with() [OK]

Hint: Use starts-with(@attr, 'text') for prefix matching [OK]

Common Mistakes:

• Using contains() instead of starts-with() for prefix
• Using CSS selector syntax like ^= in XPath
• Incorrect function syntax or missing parentheses

3. Given the following HTML snippet:

<input type="text" id="user_email" value="[e-mail]"/>

What is the result of this XPath query?
//*[@id[contains(., 'user')]]

medium

A. Syntax error due to incorrect XPath function usage

B. Selects all elements with any id attribute

C. Selects the input element because its id contains 'user'

D. Selects no elements because 'user' is not in the value attribute

Solution

1. Step 1: Analyze the XPath syntax

   The XPath //*[@id[contains(., 'user')]] is syntactically incorrect because @id is an attribute node and cannot be used as a function or have predicates applied directly like this.

2. Step 2: Correct XPath syntax

   To check if the id attribute contains 'user', the correct XPath is //*[@id[contains(., 'user')]] is invalid; instead use //*[contains(@id, 'user')].

3. Final Answer:

   Syntax error due to incorrect XPath function usage -> Option A

4. Quick Check:

   Attribute predicates must be correctly formed [OK]

Hint: Use contains(@id, 'user') not @id[contains()] [OK]

Common Mistakes:

• Using predicates directly on attribute nodes
• Assuming . refers to attribute value in this context
• Incorrect predicate syntax

4. You wrote this XPath to find links starting with "http":
//a[contains(starts-with(@href, 'http'))]
Why does this XPath fail to find any elements?

medium

A. Because @href attribute is missing

B. Because contains() cannot wrap starts-with() function

C. Because starts-with() requires two arguments

D. Because the syntax is correct but no links start with 'http'

Solution

1. Step 1: Understand function nesting rules in XPath

   The contains() function expects two string arguments, but here it wraps starts-with() which returns a boolean, causing a syntax error.

2. Step 2: Correct usage

   Use either starts-with(@href, 'http') alone or contains(@href, 'http'), but not nested.

3. Final Answer:

   Because contains() cannot wrap starts-with() function -> Option B

4. Quick Check:

   Do not nest contains() and starts-with() [OK]

Hint: Do not nest XPath functions like contains(starts-with()) [OK]

Common Mistakes:

• Nesting contains() and starts-with() incorrectly
• Assuming starts-with() returns string for contains()
• Ignoring function argument requirements

5. You want to locate all <div> elements whose class attribute starts with "alert" but excludes those that contain "dismiss" anywhere in the class. Which XPath expression correctly achieves this?

hard

A. //div[starts-with(@class, 'alert') and not(contains(@class, 'dismiss'))]

B. //div[contains(@class, 'alert') and not(starts-with(@class, 'dismiss'))]

C. //div[starts-with(@class, 'alert') or not(contains(@class, 'dismiss'))]

D. //div[contains(@class, 'alert') or contains(@class, 'dismiss')]

Solution

1. Step 1: Use starts-with() to match class beginning

   The expression starts-with(@class, 'alert') selects elements whose class attribute begins with "alert".

2. Step 2: Exclude elements containing 'dismiss'

   The not(contains(@class, 'dismiss')) excludes elements whose class contains "dismiss" anywhere.

3. Step 3: Combine conditions with and

   Both conditions must be true, so use and to combine them.

4. Final Answer:

   //div[starts-with(@class, 'alert') and not(contains(@class, 'dismiss'))] -> Option A

5. Quick Check:

   Starts with alert AND no dismiss = //div[starts-with(@class, 'alert') and not(contains(@class, 'dismiss'))] [OK]

Hint: Combine starts-with() and not(contains()) with and [OK]

Common Mistakes:

• Using or instead of and causing wrong matches
• Mixing contains() and starts-with() incorrectly
• Forgetting to negate contains() for exclusion