How it works

The behaviour that makes components accessible (focus, positioning, dismissal) runs in a small JavaScript engine driven from C#, because Blazor can't do it synchronously. This page is authored in markdown and rendered with Markdig.

The constraint

Blazor cannot synchronously manipulate the DOM: WebAssembly has no DOM, and Server marshals interop asynchronously over SignalR. So a correct focus trap, scroll lock, anchored positioning, roving tabindex, content teleport, or pointer drag must be JavaScript, driven from C#.

The engine

Navius keeps that behaviour in one engine (navius-interop.js) with C# wrappers. It is dependency-free: the anchored positioner is hand-rolled rather than pulling in a positioning library. Each primitive stays declarative and drives the engine over interop.

• focus trap, scroll lock, anchored positioning (flip / clamp / arrow)
• dismissable layers, roving focus with a nested-submenu guard
• teleport-to-body (focus-preserving), size observation, drag tracking
• constraint-validation readout, toast swipe / pause / hotkey

From brain to helm

Primitives expose ARIA, keyboard, and a data-* state contract, and forward every unmatched attribute. The helm is Tailwind on that seam: it merges its classes with yours and reproduces the state contract in CSS (data-[open], data-[checked]). Behaviour is solved once; styling is yours.