RFC: slot assigned nodes

text/0000-slot-assigned-nodes.md

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+---
+title: Slot Assigned Nodes
+status: DRAFTED
+created_at: 2026-02-05
+updated_at: 2026-02-05
+pr: https://github.com/salesforce/lwc-rfcs/pull/97
+---
+
+# Slot Assigned Nodes
+
+## Summary
+
+To observe slot data requires a bit of boilerplate. The goal would be to remove this boilerplate especially around conditional slot parents or nodes.
+
+## Basic example
+
+> Note: Normalize `nodes` by removing all `node.type === Node.TEXT_NODE` with `node.nodeValue === ''`. This simplifies logic for devs.
+> Note2: Using `slot` as the placeholder name, but could copy lit's `queryAssignedNodes()`.
+
+```typescript
+import { LightningElement, slot } from 'lwc';
+
+export default class Playground extends LightningElement {
+    showDefaultSlot = true;
+    showNameSlot = true;
+
+    @slot()
+    slotDefault(nodes) {
+        this.showDefaultSlot = nodes.length > 0;
+    }
+
+    @slot('name')
+    slotName(nodes) {
+        this.showNameSlot = nodes.length > 0;
+    }
+
+    // alternatively match lit's or support both formats
+    @slot()
+    bodyNodes: Array<Node>;
+
+    @slot('name')
+    nameNodes: Array<Node>;
+
+    get showBody() {
+        return this.bodyNodes.length > 0;
+    }
+
+    get showName() {
+        return this.nameNodes.length > 0;
+    }
+}
+```
+
+template...
+```html
+<div hidden={hasSlot}>
+  <slot></slot>
+</div>
+```
+
+## Motivation
+
+Simplifies monitoring slots by removing boilerplate. See lit's [`queryAssignedNodes()`](https://github.com/lit/lit/blob/main/packages/reactive-element/src/decorators/query-assigned-nodes.ts)
+
+## Detailed design
+
+See: [`queryAssignedNodes()`](https://github.com/lit/lit/blob/main/packages/reactive-element/src/decorators/query-assigned-nodes.ts)
+
+## Drawbacks
+
+Why should we *not* do this? Please consider:
+
+- implements another decorator for something that can be done with a few lines of code.
+- devs may also request `queryAssignedElements()`.
+
+## Alternatives
+
+Alternatively one could also support `<template lwc=if={hasSlot}>`, but this would require even more code and `MutationObserver`. Prototyped this with synthetic shadow and native shadow and while it works it might be too heavy.
+
+Not sure there is any benefit in the long run to this vs `hidden={}` syntax.
+
+## Adoption strategy
+
+Document in or below the template docs.
+
+# How we teach this
+
+Using standard naming like `lit` might make more sense. Maybe even 1:1 implementation.
+
+# Unresolved questions
+
+TBD?