Recursive Comments
Unlimited-depth comment thread where <CommentNode> renders <CommentNode> directly. Tests self-referential component recursion through the compiler, depth-unbounded hydration, and reactive inner-loop reconciliation lifted onto the signal graph via memo wrappers over prop-derived arrays.
#Preview
- FL6h ago depth 0
Quick repro request: collapse a node that has unsaved edit text in a descendant, then expand. Where does the text go?
- AC5h ago depth 1
Edit state lives on the comment node itself, so collapsing keeps the textarea mounted under the visibility branch.
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1"use client"23import { createSignal, createMemo, createContext, useContext } from '@barefootjs/client'45// <CommentNode> renders <CommentNode> directly inside its own JSX.6// The compiler emits a recursive renderChild() call in the SSR7// template and a single hydrate() registration that every depth8// shares.910interface CommentsApi {11 addReply: (parentId: number, text: string) => void12 deleteComment: (id: number) => void13 toggleReaction: (id: number, emoji: string) => void14 // ...15}1617const CommentsContext = createContext<CommentsApi>()1819function CommentNode(props: { item: Comment; depth: number }) {20 const api = useContext(CommentsContext)!2122 // Memos lift props.item.X reads onto the reactive graph.23 // Without them, an inner .map() over a prop compiles as a24 // static-array forEach over the initial snapshot — adds and25 // deletes never reach the DOM because <CommentNode>'s26 // child-prefixed scope short-circuits subsequent initChild calls.27 const replies = createMemo(() => props.item.replies)28 const reactions = createMemo(() => props.item.reactions)2930 return (31 <div data-depth={props.depth}>32 <p>{props.item.text}</p>3334 {reactions().map(r => (35 <button key={r.emoji} onClick={() => api.toggleReaction(props.item.id, r.emoji)}>36 {r.emoji} {r.count}37 </button>38 ))}3940 <ul>41 {replies().map(child => (42 <li key={child.id}>43 <CommentNode item={child} depth={props.depth + 1} />44 </li>45 ))}46 </ul>47 </div>48 )49}5051export function RecursiveCommentsDemo() {52 const [comments, setComments] = createSignal<Comment[]>(initialComments)5354 const api: CommentsApi = {55 addReply: (parentId, text) => setComments(prev => updateById(prev, parentId, c => ({56 ...c,57 replies: [...c.replies, makeComment(text)],58 }))),59 // ...60 }6162 return (63 <CommentsContext.Provider value={api}>64 <ul>65 {comments().map(c => (66 <li key={c.id}>67 <CommentNode item={c} depth={0} />68 </li>69 ))}70 </ul>71 </CommentsContext.Provider>72 )73}#Features
Self-Referential Component Recursion
CommentNode appears inside its own JSX. Phase 1 IR collection treats the call as a sibling reference, so no @bf-child import marker is emitted. Phase 2 produces a single hydrate()registration whose template calls renderChild('CommentNode', ...)on every recursion step, exercising depth-unbounded SSR rendering and per-instance hydration.
Memo-Lifted Inner Loops at Every Depth
Reading props.item.replies directly in a .map() source compiles as a static-array forEach because the loop-source detector treats props as static. Wrapping the access increateMemo(() => props.item.replies) lifts it onto the reactive graph so mapArray reconciles adds, removes, and edits at every depth — including deeply-nested replies whose ancestor CommentNode short-circuited initChild on its first run because of the child-prefixed scope.
Cross-Depth Context Propagation
A single CommentsContext.Provider wraps the root list. Action handlers (addReply, deleteComment, toggleReaction) reach leaves at arbitrary depth without prop-drilling, exercisinguseContext resolution through an unbounded chain of recursive ancestors.
Per-Node Edit Mode at Every Depth
Each comment carries its own editing flag. The conditional swap between view and edit branches reuses the same slot regardless of nesting level — the compiler emits oneinsert(...) per slot id, and that wiring works identically at depth 0 and depth N because the hydrate template is shared by every instance.
Tree-Wide Derived State
totalCount, maxDepth, and totalReactions walk the full tree on every signal update. Adding a reply five levels deep updates the top-level stat strip without touching intermediateCommentNode instances directly.
Self-referential recursion finally compiles to a clean mapArray at every depth — long-standing limitation of the old codegen.
Was the memo wrapper around props.item.replies the trick?
Right — props are static at the loop-source level, but a memo lifts it onto the reactive graph.
And context here means we never have to drill addReply into every CommentNode.
Five levels deep — the reconciler still keys correctly when I edit this one.
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Does deletion at depth N rebalance keys above? Tried it on the old version and watched a sibling unmount its inputs.
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