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Find htmlSelector for Synthetic Interactions

This document provides a comprehensive guide on how to find the htmlSelector necessary for configuring synthetic interactions such as clicks and hovers. The htmlSelector is essential for specifying which elements on a webpage should be targeted during the pre-rendering process.

What is htmlSelector?​

The htmlSelector is a string used to uniquely identify elements on a webpage based on their HTML structure. It is critical for performing synthetic interactions effectively and accurately, ensuring the correct elements are targeted during the automation of interactions in prerendering.

DOM and Shadow DOM​

The htmlSelector is contained within the DOM or the shadow DOM of the web page.

  • Document Object Model (DOM): This is the standard model that describes how all elements in a web page are arranged. The DOM represents the document as a tree of objects, which can be manipulated with languages like JavaScript.
  • Shadow DOM: This part of the web standards allows developers to create their own encapsulated HTML tags, styles, and scripts, without worrying about them conflicting with other parts of the web page. It effectively shields a part of the page’s HTML from being affected by the main document's CSS and JavaScript. This is particularly useful in complex web applications and components like web components, where you want to keep the component's internal functionality separate and hidden from the rest of the application.

Special Consideration for Shadow DOM Elements​

For elements encapsulated within a shadow DOM, prepend the selector with >>> to ensure Prerendering can accurately target and interact with these elements. The >>> notation allows the selector to "pierce" through the shadow boundary, enabling interaction with elements that are otherwise encapsulated.

Find the htmlSelector​

Finding HTML selectors effectively is a crucial skill for web developers, especially when you need to manipulate or access specific elements on a web page. Here’s a step-by-step guide to finding HTML selectors.

1. Choose Your Browser and Open Developer Tools​

First, open the Developer Tools in your web browser. You can usually do this by right-clicking on an element in the page and then selecting Inspect or by using keyboard shortcuts:

  • For Chrome, Edge, and Firefox: Press Ctrl+Shift+I (Windows/Linux) or Cmd+Option+I (Mac).
  • For Safari: First, enable the Developer menu from Safari's preferences (under the Advanced tab), then press Cmd+Option+I.

2. Inspect the Element​

With the Developer Tools open, use the Elements tab (named Inspector in Firefox) to view the HTML structure of the page. You can hover over different parts of the HTML code, and the corresponding parts of the web page will be highlighted.

3. Identify and Copy the Selector​

There are several considerations for choosing the selector.

Use the ID​

If the element has an id attribute, this can serve as a straightforward selector. Example: #login-button.

Use a Complex Selector​

For elements without an id, or when a more specific path is needed, use the right-click context menu over the highlighted HTML code in the Developer Tools and select Copy > Copy selector. This gives you a string that uniquely identifies the element in CSS terms. This might be a combination of element types, classes, IDs, and pseudo-classes.

For Shadow DOM Elements​

If the element is within a shadow DOM, use >>> followed by the specific selector. For example, >>> #__next > div > header > div.chakra-container.css-1ichkct > div > div.chakra-stack.css-jojt9m > a.chakra-link.css-i0nad5.

  • You might need to use JavaScript to access the shadowRoot of the custom element. For example: document.querySelector('custom-element').shadowRoot.querySelector('element').
  • Some browsers' Developer Tools allow you to inspect elements within Shadow DOM directly. Ensure that the option to show user agent shadow DOM is enabled in the settings of the Developer Tools.

Consider Specificity and Efficiency​

The automatically generated selector might not always be the most efficient or simplest. It might be overly specific. Simplify the selector if possible, keeping only the parts that are necessary to uniquely identify the element.

For example, if the generated selector is html > body > div:nth-child(3) > div > p > a, and you know the div element has the id login-container, you might simplify this to #login-container > p > a.

Testing the htmlSelector​

Once you have identified a potential htmlSelector, it's important to test its functionality:

1. Open the Console Tab in Developer Tools​

Within the Developer Tools, find and click on the Console tab. This is where you can run JavaScript code directly against the page you are viewing.

2. Test Your Selector​

In the console, you can use the document.querySelector() method to test your selector. This method returns the first element within the document that matches the specified selector, or null if there are no matches. Here’s how to use it:

  • Type document.querySelector("yourSelector") into the console, replacing "yourSelector" with the CSS selector you want to test.
  • Press Enter to run the command.

Example

If you want to test a selector for an element with the ID login-button, you would type:

document.querySelector("#login-button")

If the selector is correct and the element exists, the console will display the HTML of that element. If the selector is incorrect or no element matches, it will return null.

3. Analyze the Results​

  • If the element appears in the console, inspect the output to ensure it’s the correct element you intended to select.
  • If null is returned, double-check your selector for any errors, such as typos, incorrect classes, or IDs. You may also need to ensure that the element is not dynamically loaded after some interactions, which might require waiting for certain events before the element can be targeted.

4. Adjust as Necessary​

If the initial test doesn't return the correct element, then modify your selector and test again. This iterative process helps refine your selector to be both accurate and efficient.

Best Practices​

These best practices helps ensure that the selectors used in prerendering scenarios are reliable, maintainable, and effective in driving the intended synthetic interactions.

Prioritize Stability in Selectors​

Choose selectors that are less likely to change. Avoid using dynamically generated classes or IDs that might vary between sessions or deployments. Opt for selectors based on stable structural elements or attributes that are consistent across different states of the application.

Use Data Attributes​

Consider using custom data attributes (for example, data-test-id="submit-button") for critical elements that are interacted with during synthetic interactions. This approach isolates the selector from style and structural changes, making your tests more resilient to changes in the design.

Minimize Dependency on DOM Structure​

Avoid selectors that are overly dependent on the DOM hierarchy, such as descendant selectors that traverse multiple layers (such as div > ul > li > a). These can break if there are changes in the structure of the DOM. Instead, use direct child selectors (such as div > a) or even better, selectors that target elements directly.

Incorporate Robustness to Dynamic Content​

For elements that might appear as part of dynamic content loading, ensure your selectors are robust. This might involve waiting for elements to become visible or checking for the presence of an element before interacting with it in your scripts.

Explicit State Selectors​

For interactions like hover or focus, explicitly define selectors that mimic these states. For example, using :hover or :focus within your CSS or when scripting interactions to ensure that the state is considered during the prerendering process.

Testing and Validation​

Regularly test your selectors as part of your prerendering process. Ensure they not only find the elements but also trigger the intended interactions correctly across all scenarios and edge cases.

Document Selector Intent​

Clearly document what each selector is targeting and why it’s chosen, especially for those involved in the synthetic interactions. This documentation is invaluable for maintenance and when modifications are needed as the application evolves.

Cross-Browser Compatibility​

Verify that your selectors and their synthetic interactions work consistently across all targeted browsers. This ensures that the prerendered content behaves as expected, regardless of the user's browser.

Feedback Loops​

Implement mechanisms to capture and review the success rate of interactions triggered by your selectors. Use this feedback to refine and improve the selector strategy continuously.

Accessibility Considerations​

Ensure that the elements targeted for synthetic interactions are also accessible. This not only improves the quality of your prerendered pages but also ensures compliance with web accessibility standards.