layoutif

Layoutif is a term used in discussions of user interface design to describe a declarative mechanism for expressing conditional layouts within a layout specification. It imagines a method for selecting among alternative spatial arrangements based on runtime conditions, without requiring imperative scripting.

In a layoutif model, decisions about how content is arranged are governed by conditions that can depend on factors such as viewport size, device orientation, content length, or user preferences. The core idea is to choose between predefined layout configurations in a way that is still part of the layout specification, rather than in separate logic or event handlers. A typical illustration might be described as: if a condition is met, apply layout A; otherwise, apply layout B.

Layoutif is often discussed in relation to existing responsive design concepts. It shares goals with CSS media queries and responsive grids by aiming to adapt structure to context, but it emphasizes a declarative selection mechanism within the layout model itself rather than external styling rules alone. Compared with imperative layout logic, layoutif seeks to express spatial decisions more directly, aligning with approaches such as constraint-based layouts and component-driven design.

Implementation considerations include performance of evaluating conditions during layout passes, readability of the conditional rules, and how changes to conditions interact with accessibility and user expectations. Critics caution that overly complex conditional layouts can be harder to maintain and test, and that portability across platforms may be limited.

See also: responsive design, media queries, CSS Grid, constraint layouts, conditional rendering.