Nicholas Barker's blog post introduces Clay, a declarative UI layout library he authored. Clay distinguishes itself by focusing solely on layout, deliberately omitting features like rendering or state management, allowing it to integrate seamlessly with various rendering technologies like HTML, Canvas, WebGL, or even server-side SVG generation. This separation of concerns promotes flexibility and allows developers to choose the rendering method best suited for their project.
The library employs a constraint-based layout system, allowing developers to define relationships between elements using a concise and expressive syntax. These constraints, expressed through functions like center, match, above, and below, govern how elements are positioned and sized relative to one another. This approach facilitates dynamic and responsive layouts that adapt to different screen sizes and orientations.
Clay’s API is designed for clarity and ease of use, promoting a declarative style that simplifies complex layout definitions. Instead of manually calculating positions and dimensions, developers describe the desired relationships between elements, and Clay's engine handles the underlying calculations. This declarative approach enhances code readability and maintainability, reducing the likelihood of layout-related bugs.
The post provides illustrative examples demonstrating how to use Clay’s functions to achieve various layout arrangements. These examples showcase the library's versatility and its ability to handle both simple and intricate layouts. The author emphasizes the library's small size and efficiency, making it suitable for performance-critical applications. Further, its focused nature avoids the "kitchen sink" problem common in larger UI libraries, keeping the API lean and intuitive. By concentrating solely on layout, Clay avoids feature bloat and remains a lightweight, specialized tool that can be readily integrated into diverse projects. The post concludes by inviting readers to explore the library's source code and documentation, encouraging contributions and feedback from the community.
The Mozilla Developer Network (MDN) web documentation article titled "Contain – CSS Cascading Style Sheets" elaborates on the contain CSS property, a powerful tool for optimizing website performance by isolating specific elements from the rest of the document. This isolation limits the browser's calculations for layout, style, and paint, which can significantly improve rendering speed, especially in complex web applications. The contain property achieves this by declaring that an element's subtree (its descendants) are independent and their changes won't affect the layout, style, paint, or size calculations of the rest of the page, or vice-versa.
The article details the various values the contain property can accept, each offering different levels of isolation:
strict: This value provides the strongest level of containment. It encapsulates the element completely, meaning changes within the element will not trigger layout, paint, style, or size recalculations outside of it, nor will external changes affect it. It essentially treats the element as an entirely separate document.
content: This value signifies that the element's contents are independent in terms of layout, style, and paint. Changes within the contained element won't affect the layout or styling of the rest of the document, and vice-versa. Size containment, however, is not implied.
size: This value indicates that the element's dimensions are fixed and known beforehand. This allows the browser to allocate space for the element without needing to examine its descendants, which can expedite layout calculations. Crucially, size containment requires the element to have a specified size (e.g., through properties like width and height). Otherwise, it defaults to a size of 0, potentially hiding the content. This value does not isolate style, layout, or paint.
layout: This isolates the element's layout. Changes in the element's internal layout won't affect the layout of the surrounding elements, and external layout changes won't affect the contained element's internal layout.
style: This prevents style changes within the contained element from leaking out and affecting the styling of the parent document, and likewise, external style changes won't influence the element's internal styling. This particularly applies to style inheritance and counter incrementing. Note: As of the documentation's current state, style containment is still experimental and may not be fully supported by all browsers.
paint: This value ensures that the element's painting is contained within its boundaries. Any painting done within the element won't overflow outside its box, and painting from other elements won't bleed into the contained element. This is particularly useful for elements with effects like shadows or filters, preventing them from overlapping adjacent content.
The article also clarifies that multiple values can be combined, separated by spaces, to provide a composite containment effect. For example, contain: layout paint would isolate both layout and paint. Using the keyword contain: none explicitly disables containment, ensuring no isolation is applied.
Finally, the MDN documentation highlights important considerations for using the contain property effectively. It emphasizes the need for careful planning when implementing containment, especially with the size value, due to its potential to inadvertently hide content if dimensions are not explicitly defined. Overall, the article positions the contain property as a valuable tool for web developers aiming to optimize rendering performance, but it stresses the importance of understanding its nuances to avoid unexpected behavior.
The Hacker News post titled "Contain – CSS Cascading Style Sheets – MDN" linking to the MDN documentation on the CSS contain property has a moderate number of comments discussing various aspects of the property and its usage.
Several commenters highlight the performance benefits of contain. One user emphasizes how crucial this property is for optimizing web performance, particularly in complex applications. They elaborate that contain allows developers to isolate specific parts of the DOM, thereby limiting the scope of reflows and repaints, leading to smoother interactions and faster rendering times. This sentiment is echoed by another comment which points out the significant impact contain can have on improving rendering performance, especially in situations with animations or transitions.
Another thread discusses the nuances of the different values of the contain property (like size, layout, style, and paint). One user questions the practical applications of style containment, leading to a discussion about scenarios where preventing style bleed from a component is beneficial, such as in shadow DOM implementations or when dealing with third-party embedded content. The utility of size containment is also highlighted, specifically for scenarios where the size of a component is known beforehand, enabling the browser to perform layout calculations more efficiently.
One commenter expresses surprise at not having known about this property sooner, suggesting that it's underutilized within the web development community. This comment sparks further discussion about the discoverability of useful CSS properties and the challenges developers face in keeping up with the evolving web standards.
A few comments dive into specific use cases for contain. One user mentions using it to isolate a complex animation, preventing performance issues from affecting the rest of the page. Another explains how contain can be instrumental in optimizing the performance of virtualized lists, where only visible items need to be rendered.
Finally, a commenter points to the MDN documentation itself as an excellent resource for understanding the intricacies of the contain property and its various values, underscoring the value of the original link shared in the Hacker News post. The commenter highlights the detailed explanations and examples provided in the documentation, which allows for a deeper understanding of its effects and proper implementation.
Summary of Comments ( 87 )
https://news.ycombinator.com/item?id=42463123
HN users generally praised Clay's approach to layout, highlighting its use of constraints, which some compared favorably to CSS Flexbox and Grid. Several appreciated its focus on solving layout problems specifically, rather than trying to be an all-encompassing UI framework. The lack of browser support and the potential performance implications of using WebAssembly were raised as concerns. Some commenters questioned the choice of Rust/WebAssembly and suggested alternatives like native JavaScript or compiling to WebAssembly from a language with better JavaScript interoperability. The project's early stage of development was also noted, with several users expressing interest in its future progress. Some discussed the complexity of layout systems and whether Clay's constraint-based approach offered significant advantages over existing solutions.
The Hacker News post titled "Clay – UI Layout Library" discussing Nic Barker's new layout library has generated a modest amount of discussion, focusing primarily on comparisons to existing layout systems and some initial impressions.
Several commenters immediately draw parallels to other layout tools. One points out the similarities between Clay and the CSS Flexbox model, suggesting that Clay essentially replicates Flexbox functionality. This comparison is echoed by another user who expresses a preference for leveraging the browser's native Flexbox implementation, citing concerns about potential performance overhead with a JavaScript-based solution like Clay.
Another commenter delves into a more detailed comparison with Yoga, a popular cross-platform layout engine. They highlight that Clay adopts a constraint-based approach similar to Yoga but implemented in WebAssembly for potential performance benefits. The comment emphasizes Clay's novel use of “streams” to update layout properties, contrasting it with Yoga's more traditional recalculation methods. This distinction sparks further discussion about the potential advantages and disadvantages of stream-based layout updates, with some speculating about its impact on performance and ease of use in complex layouts.
Performance is a recurring theme. One comment questions the actual performance gains of using WebAssembly for layout calculations, pointing to potential bottlenecks in JavaScript interoperability. This raises a larger discussion about the optimal balance between native browser capabilities and JavaScript-based libraries for layout management.
A few comments focus on the specific design choices within Clay. One user questions the decision to expose low-level layout primitives rather than providing higher-level abstractions, leading to a conversation about the trade-off between flexibility and ease of use in a layout library. Another comment highlights the benefit of Clay’s explicit sizing model, suggesting it helps avoid common layout issues encountered in other systems.
Overall, the comments demonstrate a cautious but intrigued reception to Clay. While acknowledging the potential benefits of its WebAssembly implementation and novel stream-based updates, commenters express reservations about its performance relative to native browser solutions and question some of its design choices. The discussion ultimately revolves around the ongoing search for the ideal balance between performance, flexibility, and ease of use in UI layout management.