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Select all that apply. What can you do to optimize images within a custom module?

 

• Set the image’s loading attribute to “lazy,” by default
• Add width and height attributes to the image
• Use the resize_image_url function to resize the image
• Use srcset and sizes attributes

 

Explanation: When optimizing images within a custom module, there are several techniques you can employ to improve performance and accessibility. Setting the image’s loading attribute to ’lazy,’ by default is a recommended practice to defer the loading of images until they are within the user’s viewport, reducing initial page load times and conserving bandwidth, especially for images below the fold. Adding width and height attributes to the image specifies the dimensions of the image in the HTML markup, allowing the browser to allocate space for the image while it’s loading, preventing layout shifts and improving rendering performance. Using the resize_image_url function to resize the image dynamically generates resized versions of the image, reducing file size and optimizing images for various viewport sizes and device resolutions, enhancing page load speed and user experience. Using srcset and sizes attributes enables you to provide multiple image sources and specify different image sizes based on the user’s device capabilities and viewport size, ensuring that the browser can select the most appropriate image for display, further optimizing performance and responsiveness. By implementing these optimization techniques, you can significantly improve the loading speed, user experience, and accessibility of images within custom modules on your website.

If your site has consistently poor Total Blocking Time scores, which approach should you take to improve this metric?

• Remove all videos from your site that are 1MB or larger
• Optimize images and use srcset and sizes attributes to provide the browser multiple image options depending on the user’s device
• Self-host fonts instead of fetching them from a third party
• Reduce the total amount of JavaScript loaded on your site while also efficiently loading the site’s JavaScript

 

Explanation: The correct approach to improve consistently poor Total Blocking Time (TBT) scores is to reduce the total amount of JavaScript loaded on your site while also efficiently loading the site’s JavaScript. Total Blocking Time measures the total amount of time between First Contentful Paint (FCP) and Time to Interactive (TTI) during which the main thread is blocked and unable to respond to user input. High TBT scores indicate that JavaScript execution is blocking the main thread, causing delays in rendering and interactivity, which can lead to a poor user experience. By reducing the total amount of JavaScript loaded on the site, developers can minimize the time spent parsing, compiling, and executing JavaScript code, thereby reducing TBT. Strategies to achieve this include removing unnecessary or redundant JavaScript, optimizing code for performance, implementing code-splitting techniques to load only essential scripts initially, and deferring the loading of non-critical scripts. Additionally, optimizing the delivery of JavaScript resources, such as leveraging browser caching, using asynchronous loading techniques, and minifying code to reduce file size, can further improve TBT scores. Overall, prioritizing JavaScript optimization efforts is crucial for enhancing Total Blocking Time metrics and ensuring a smoother, more responsive browsing experience for users.

Fill in the blank. To provide a good user experience, a Largest Contentful Paint of ___________ or less is recommended.

• 3 seconds
• 5 seconds
• 2.5 seconds
• 1 second

 

Explanation: The correct answer is 2.5 seconds. Largest Contentful Paint (LCP) measures the render time of the largest content element visible within the viewport, typically an image or a block of text. It is a key metric for user-centric performance because it indicates when the main content of a web page has loaded, thus providing users with a meaningful visual experience. An LCP of 2.5 seconds or less is recommended to ensure that users perceive the web page as fast and responsive. Pages with faster LCP scores tend to have lower bounce rates and higher engagement levels, contributing to improved user satisfaction and retention. By optimizing for a fast LCP, developers can prioritize the loading of critical resources, such as images and text, and implement performance best practices like lazy loading, resource prioritization, and efficient asset delivery to enhance the overall user experience. Ultimately, aiming for an LCP of 2.5 seconds or lower helps create a more engaging and enjoyable browsing experience for website visitors, leading to increased user engagement and improved business outcomes.

Fill in the blank. Many browsers support native image lazy-loading using the _________ attribute.

• defer
• async
• preload
• loading

 

Explanation: The correct answer is loading. The loading attribute is used to enable native lazy-loading for images in HTML documents, allowing browsers to defer the loading of offscreen images until they are needed. By adding the loading='lazy' attribute to an <img> tag, developers can instruct the browser to delay the loading of images that are not immediately visible within the viewport, thereby improving page loading performance and reducing bandwidth consumption. This attribute is particularly useful for web pages with a large number of images or long-scrolling content, as it helps prioritize the loading of visible content while deferring the loading of non-visible images until the user scrolls closer to them. Additionally, native lazy-loading provided by the loading attribute is supported by most modern browsers, making it a convenient and widely-compatible solution for optimizing image loading in web applications. Overall, the loading attribute enhances the user experience by speeding up page load times and conserving network resources, making it a valuable tool for web developers striving to create fast and efficient websites.

Fill in the blank. Defer loading of non-critical CSS by adding ______ as an argument in your require_css function call.

• { defer: true }
• { position: footer }
• { type: defer }
• { async: true }

 

Explanation: The correct answer is { async: true }. When dealing with non-critical CSS resources, it’s often beneficial to defer their loading to improve page loading performance. By adding the { async: true } argument in the require_css function call, you instruct the browser to load the specified CSS file asynchronously. Asynchronous loading allows the browser to continue parsing and rendering the HTML content without waiting for the CSS file to be fully downloaded and processed. This approach prevents CSS resources from blocking the rendering of the page, resulting in faster initial page load times and a better user experience. Additionally, deferring non-critical CSS loading can help prioritize the loading of critical resources, such as HTML content and essential CSS styles, leading to quicker page rendering and improved perceived performance. Overall, leveraging asynchronous loading techniques for non-critical CSS resources is a recommended practice for optimizing web page loading speed and enhancing overall performance.

Fill in the blank: The ___________ is a combination of both the DOM and CSSOM.

• render tree
• Largest Contentful Paint
• Cumulative Layout Shift
• Critical Rendering Path

 

Explanation: The correct answer is render tree. In web development, the render tree is a crucial concept representing the combination of both the DOM (Document Object Model) and the CSSOM (Cascading Style Sheets Object Model). While the DOM represents the structure of the HTML content on a web page, and the CSSOM represents the styles applied to that content, the render tree merges these two models to create a cohesive structure that incorporates both the content and its styling. The render tree includes only the elements that will be displayed on the page, taking into account factors such as visibility, display property, and CSS properties like display: none. This combined representation is essential for the browser’s rendering engine to calculate the layout of the page accurately and determine how each element should be displayed visually. Thus, the render tree serves as the foundation for the browser’s rendering process, ensuring that the web page is presented to users correctly according to its HTML structure and CSS styles.