UI.Modal

UI.Modal(input: Input): Node

Creates an accessible dialog above the current screen, moves focus to an optional declared child, relates visible descriptive text, traps navigation, and restores the originating focus after dismissal.

Mental model

This is a declarative node: app.render describes it again from current state, while the host matches its stable id to the existing view.

Before you use it

Add luastra/ui to this module's dependencies in luastra.json, then import it with require("luastra/ui"). The project must declare the ui.render capability. app.render must return one UI.Screen root; place this node inside that tree rather than invoking it for a hidden side effect.

How it fits

The constructor validates its fields immediately and returns a UI.Node. After app.render returns, the host reconciles that node by stable id with the current semantic DOM-based interface. Current desktop and mobile hosts package the same web artifact; native adapters are used at capability boundaries.

Shared parameter groups

Parameters

Children and layout

Heading, content, and close action.

Accessibility and keyboard

The host traps focus inside the open dialog, Escape invokes onDismiss, and closing restores focus to the trigger.

Common mistakes

• Removing the close button and relying only on Escape.
• Rendering interactive content outside and above an open modal.

Returns

Node — a validated declarative UI node that becomes part of the next host-neutral render tree.

What happens next

A validated declarative node appears after it is returned as part of the current render tree.

Failures and fixes

Invalid fields, duplicate IDs, unsupported child combinations, or a missing ui.render capability fail during check, render-tree validation, or host startup.

Availability

Source API in 0.5.0-alpha; the public installer targets 0.5.0-alpha. Verify host-specific behavior against the selected SDK.

Focused example

UI.Modal {
    id = "help/modal",
    open = helpOpen,
    label = "Help",
    onDismiss = "help.close",
    UI.Text { id = "help/title", text = "Help", variant = "heading" },
    UI.Button { id = "help/close", text = "Close", onTap = "help.close" },
}

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