How to Use Playwright Locators_ A Detailed Guide.pdf

How to Use Playwright Locators: A
Detailed Guide
Automated testing has become indispensable for ensuring the reliability and
performance of web applications. End-to-end testing frameworks like
Playwright have emerged as powerful tools enabling developers and testers to
simulate real user interactions across browsers. A fundamental aspect of
effectively using Playwright is mastering Playwright Locators—tools that allow
precise identification and manipulation of web elements.
This detailed guide aims to comprehensively understand Playwright Locators,
their types, usage, and best practices to enhance your automation testing
strategies.
Read: A Complete Guide to Web App Testing
What is Playwright?

Playwright is an open-source Node.js library developed by Microsoft to
automate web browsers. It provides a high-level API to control Chromium and
WebKit, enabling cross-browser testing with a single codebase. Playwright is
designed to be reliable, fast, and capable of handling modern web
applications that heavily rely on JavaScript.
Key Features of Playwright
● Cross-Browser Support: Automate tests across Chromium, Firefox,
and WebKit.
● Auto-Wait Mechanism: Automatically waits for elements to be ready
before performing actions.
● Isolation Model: Offers browser contexts that isolate cookies and
cache, making parallel testing more efficient.
● Network Control: Intercept and modify network requests and
responses.
● Extensive API: Provides a rich set of functionalities for various testing
needs.
Installing and Setting Up Playwright
Prerequisites
● Node.js: Ensure you have Node.js (version 14 or higher) installed.
● Package Manager: npm or Yarn.
Installing Playwright

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# Using npm
npm init playwright@latest
# Using Yarn
yarn create playwright
Project Initialization
1. Create a New Directory:
mkdir playwright-tests
cd playwright-tests
2. Initialize the Project:
npm init -y
Browser Installation
Playwright manages browser binaries internally. To install browsers:
npx playwright install
Getting Started with Playwright
Writing Your First Test

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Let's write a simple test to ensure the Playwright website's title contains
"Playwright".
Step 1: Create a Test File
Create a new file named example.spec.ts inside the tests directory:
touch tests/example.spec.ts
Step 2: Write the Test Code
Open example.spec.ts in your code editor and add the following code:
import { test, expect } from '@playwright/test';
test('has title', async ({ page }) => {
await page.goto('https://playwright.dev/');
// Expect the title to contain "Playwright".
await expect(page).toHaveTitle(/Playwright/);
});
Step 3: Add Another Test (Optional)
Let's add another test to interact with a page element:
test('get started link', async ({ page }) => {
await page.goto('https://playwright.dev/');

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// Click the "Get started" link.
await page.getByRole('link', { name: 'Get started'
}).click();
// Expect the page to have a heading with the name
"Installation".
await expect(page.getByRole('heading', { name:
'Installation' })).toBeVisible();
});
Running the Tests
To run your tests, use the Playwright test runner command:
npx playwright test
The test runner will search for files matching *.spec.ts or *.spec.js in
the tests directory and execute them.
Expected Output
You should see an output similar to:
Running 2 tests using 1 worker
✔ [chromium] › tests/example.spec.ts:3:1 › has title (2s)
✔ [chromium] › tests/example.spec.ts:10:1 › get started
link (1s)
2 passed (3s)

This indicates that both tests have passed successfully.
Understanding Playwright Locators
What Are Locators?
Locators in Playwright are objects used to find elements on a web page. They
are the cornerstone for interacting with web elements—clicking buttons,
entering text, selecting options, and more. By using locators, you can write
scripts that mimic real user actions, essential for thorough end-to-end testing.
Purpose of Locators
● Element Identification: Precisely target elements for interaction.
● Automation: Simulate user behavior in a consistent and repeatable
manner.
● Verification: Assert the state and properties of elements during tests.
● Maintainability: Write resilient tests that withstand changes in the
application's UI.
Locators vs. Selectors
● Selectors: Strings that describe locating elements in the DOM, such
as CSS selectors or XPath expressions.‍
● Locators: Abstractions built on selectors that offer additional
methods for interaction and assertions. They provide a more robust
and flexible way to work with elements.
When to Use Locators vs. Selectors

Use Locators When Use Selectors When
You need to interact with
elements (click, fill, check).
You need a quick one-time query for an
element.
You want to assert properties or
states of elements.
You are working with legacy code that uses
selectors.
You prefer readable and
maintainable code.
Performance is critical, and you want to
minimize overhead (though the difference is
often negligible).
You need to handle dynamic
content that may change
between actions.
Drawbacks of Using Selectors Directly vs. Advantages of
Using Locators
Drawbacks of Using Selectors Directly Advantages of Using Locators
Brittleness: Selectors are tightly
coupled with the DOM structure,
making them more fragile and prone to
breaking if the UI changes.
Resilience: Locators handle dynamic
web pages gracefully by waiting for
elements to appear and be actionable,
enhancing test reliability.
Lack of Advanced Features: Selectors
lack the rich API that locators provide
for interactions and assertions, limiting
their functionality in complex test
scenarios.
Rich API: They provide interaction
methods (click, fill, check, etc.) and
assertions (isVisible, isEnabled),
offering more functionality than
selectors.

Eager Evaluation: Selectors are
evaluated immediately, which can lead
to errors if the element is not yet
present in the DOM, causing potential
race conditions.
Lazy Evaluation: Locators evaluate
elements at the time of action, reducing
the likelihood of race conditions and
errors due to elements not being
immediately present.
Maintenance Overhead: Using raw
selectors can make the code less
readable and harder to maintain,
especially in large test suites where
code clarity is crucial.
Improved Readability: Code written
with locators is generally more readable
and easier to understand, improving
maintainability, especially in larger test
suites.
Importance in Testing
Using locators effectively is crucial for the following:
Test Reliability
Test reliability reduces false negatives caused by flaky tests. Precise and
robust locators ensure that your test scripts interact with the correct web
elements every time. By accurately identifying elements, you reduce the risk of
tests failing due to elements not being found or incorrect elements being
manipulated.
Efficiency
Locator efficiency minimizes the time spent writing and maintaining tests.
Effective locators simplify your test scripts, making them more readable and
easier to maintain. Using straightforward and consistent locator strategies

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reduces the time spent debugging and updating tests. When the application's
UI changes, well-crafted locators are easier to adjust.
Scalability
Locator scalability allows tests to grow with the application without becoming
unmanageable. As your application grows, the number of elements and
interactions increases. Using modular and reusable locator strategies allows
your tests to scale alongside your application without becoming unwieldy.
Overview of Locator Syntax
Locators are created using methods like page.locator(selector) and
can be manipulated using chaining methods for actions and assertions.
const button = page.locator('button.submit');
await button.click();
Types of Playwright Locators
Playwright offers a variety of locators to suit different test scenarios.
Understanding these helps in selecting the most effective locator for each
element.
Label locators

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The getByLabel locator allows you to find elements that contain a specific
text string. It searches through the page's rendered text content and matches
elements whose visible text corresponds to the provided value.
const emailInput = page.getByLabel('Email Address');
await emailInput.fill('user@example.com');
Placeholder locators
The getByPlaceholder locator finds input elements using their placeholder
attribute value. The placeholder text is the hint or example text displayed
inside input fields when empty.
const searchInput = page.getByPlaceholder('Search');
await searchInput.fill('Playwright');
AltText locators
The getByAltText locator finds elements with an alt attribute matching
the specified text, commonly used with images (<img> tags). The alt
attribute provides alternative information for an image if a user cannot view it
and is a key component of web accessibility.

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const logoImage = page.getByAltText('Company Logo');
await expect(logoImage).toBeVisible();
Title locators
The getByTitle locator allows you to find elements by their title attribute
value. The title attribute is often used to provide additional information
about an element, typically displayed as a tooltip when the user hovers over it.
const tooltipElement = page.getByTitle('Additional
Information');
await expect(tooltipElement).toBeVisible();
Test ID locators
The getByTestId locator is designed to find elements using a data attribute
specifically for testing purposes, such as data-testid. Using a dedicated
attribute for test selection, you decouple your tests from the styling and
structure of the application, making them more resilient to changes in the UI.
const menu = page.getByTestId('main-menu');
await menu.click();

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Text Locators
Matching by text helps target elements with their visible text content. It is
useful to find elements containing specific text that are useful for buttons or
links.
// Using getByText()
const button = page.getByText('Submit');
await button.click();
Role Locators
Select elements based on their ARIA roles, improving accessibility testing.
Role selectors allow tests to interact with elements in the same way assistive
technologies interpret and engage with web content.
// Using getByRole()
const checkbox = page.getByRole('checkbox', { name:
'Subscribe to newsletter' });
await checkbox.check();
CSS Selectors
CSS selectors help select elements in browsers effectively and efficiently.
Utilize standard CSS syntax to select elements based on classes, IDs,
attributes, and hierarchical relationships.

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// Select by class
const element = page.locator('.my-class');
// Select by ID
const element = page.locator('#my-id');
// Select by attribute
const element = page.locator('input[name="username"]');
XPath Selectors
XPath selectors help select elements based on their HTML content and
structure. Leverage XPath Path language to navigate the DOM tree.
const element =
page.locator('//div[@class="container"]//a[text()="Learn
more"]');
Nth Selectors
Target elements based on their position in a list or hierarchy.
// Select the third item in a list
const item = page.locator('ul > li').nth(2);
React Selectors

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For applications built with React, Playwright provides special selectors to
locate components by their name or props, facilitating testing of
React-specific components.
// Selecting a React component by its name
const component = page.locator('_react=MyComponent');
// Selecting a component with specific props
const componentWithProps =
page.locator('_react=MyComponent[foo="bar"]');
// Interacting with a component's method (if exposed)
await component.evaluate((node) => {
// Access component's methods or state
});
Note: React selectors rely on internal knowledge of the application's
component hierarchy and require the application to be in development mode.
They are particularly useful when you can access the component's source
code and need to test components in isolation.
Vue Selectors
Similarly, for Vue.js applications, Playwright offers selectors the ability to
locate Vue components by name or props.
// Selecting a Vue component by its name

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const component = page.locator('_vue=MyComponent');
// Selecting a component with specific props
const componentWithProps =
page.locator('_vue=MyComponent[title="Welcome"]');
// Accessing component data
await component.evaluate((node) => {
// Interact with the component's data or methods
});
Note: Vue selectors require the application to expose component details and
are best used in development environments. They allow for more granular
testing of Vue components, especially when you need to interact with
component-specific properties or methods.
Best Practices for Effective Locator
Usage
Leverage Playwright's Built-in Locators
Playwright's locators come with auto-waiting and retry mechanisms, ensuring
actions are performed on ready elements.
Example:
// 👍 Good Practice
await page.getByRole('button', { name: 'Submit' }).click();

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Prefer User-Facing Attributes to XPath or CSS Selectors
Relying on the DOM structure or CSS classes can lead to fragile tests that
break when the UI changes. Instead, use locators based on user-facing
attributes like roles and accessible names.
Example:
// 👎 Bad Practice
page.locator('button.btn-primary');
// 👍 Good Practice
page.getByRole('button', { name: 'Submit' });
Leverage Auto-Waiting
Playwright automatically waits for elements to be actionable before
performing actions on them. Utilize this feature to write cleaner code without
explicit waits.
Example:
// No need for explicit wait
await page.getByRole('button', { name: 'Submit' }).click();
Use Data Attributes for Stable Selectors

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Consider adding custom data-testid attributes to your elements when
built-in locators are insufficient. This provides a stable way to locate less likely
to change elements.
await page.getByTestId('submit-button').click();
Use Class Names Carefully
Class names can be used when IDs or accessibility IDs are not available.
However, they may not be unique and can change if the UI is updated.
Considerations:
● Non-Unique: Multiple elements may share the same class.
● Maintenance: Changes in styles can affect selectors.
Example:
await page.locator('.submit-button').click();
Utilize Native Locator Strategies When Necessary
Playwright supports native locator strategies interpreted by the underlying
automation frameworks, such as -android uiautomator, -ios
predicate string, and -ios class chain.

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Example:
// Using Android UIAutomator await
page.locator('android=UiSelector().text("Submit")').click()
;
Use Image Locators as a Last Resort
Image locators (-image) allow you to find elements based on images. While
useful in certain scenarios, they should be used sparingly.
Example:
await page.locator('image=path/to/image.png').click();
Using Playwright with HeadSpin
To use Playwright with HeadSpin, first start a browser session.
Launch the Browser with HeadSpin CLI:
Run the Node.js script or command to start the browser session:
const { spawn } = require('node:child_process');

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sp = spawn(
'hs',
[
'connect',
'browser',
'-t', 'your_headspin_api_token',
'device_specifier'
],
);
Alternatively, execute the command directly in the terminal:
hs connect browser -t your_headspin_api_token
device_specifier
● Run the hs connect command:
Sample piece of code that imports Playwright:
Run the Playwright Tests:
● Execute your test script to check Playwright functionality:

node playwright_android.js
● This will run all the test cases your script defines against the browser on the
mobile Android device that is hs connected.
● If it runs successfully, you will see the URL opening on the device.
● You can check the test on the HeadSpin Platform.
● The test will open a new tab and navigate to the specified webpage - in this
case - example.com.
● In your terminal, you see how Playwright opens the webpage and grabs its
title.
Enhancing Testing with HeadSpin
Integration
While Playwright provides robust tools for automation, integrating it with a
platform like HeadSpin can significantly boost your testing capabilities.
Use Cloud-Based Testing Environments
● Scalability: Run tests across multiple environments without local
setup.

● Accessibility: Access a wide range of browsers and devices.
Run Tests in Parallel
● Efficiency: Reduce test execution time by running tests concurrently.
● Coverage: Test multiple scenarios simultaneously.
Monitor Test Performance and Results
● Analytics: Gain insights through detailed performance metrics.
● Reporting: Generate comprehensive test reports.
Integrate into CI/CD Pipelines
● Automation: Trigger tests automatically on code changes.
● Consistency: Ensure that every build is tested thoroughly.
Ensure Tests Are Maintainable and Scalable
● Modular Design: Write reusable code components.
● Version Control Integration: Keep track of changes and collaborate
effectively.
Conclusion
Mastering Playwright Locators is a pivotal step in enhancing your end-to-end
testing strategy. By understanding the various locator types and best
practices, you can write tests that are reliable, maintainable, and reflective of
real user interactions.

Integrating Playwright with advanced testing platforms like HeadSpin further
amplifies your testing efficiency. The combination of robust locator strategies
and powerful testing tools ensures that your web applications are thoroughly
tested, delivering high-quality software to users.
This article was originally published on:
https://www.headspin.io/blog/playwright-locators-guide

How to Use Playwright Locators_ A Detailed Guide.pdf

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