Class: RetreeLink<TNode>#

Defined in: Retree.ts:114

Reactive pointer to a Retree-managed node owned somewhere else.

Remarks#

RetreeLink is created by Retree.link. Store it in a Retree tree when one part of state needs to point at another node without becoming that node's structural parent. Replacing RetreeLink.current emits for the link. Mutating current emits from the target's structural location.

Most code should call Retree.link instead of constructing this class directly.

Example#

const root = Retree.root({
    tasks: [{ title: "Docs" }],
    selected: null as RetreeLink<{ title: string }> | null,
});

root.selected = Retree.link(root.tasks[0]);
root.selected.current.title = "Better docs";

Extends#

• ReactiveNode

Type Parameters#

Constructors#

Constructor#

new RetreeLink<TNode>(node): RetreeLink<TNode>;

Defined in: Retree.ts:126

Parameters#

Returns#

RetreeLink<TNode>

Overrides#

ReactiveNode.constructor

Properties#

Accessors#

dependencies#

Get Signature#

get dependencies(): never[];

Defined in: Retree.ts:132

Dependencies to listen for changes to.

Remarks

When any IReactiveDependency criteria is met, a change will be emitted for this ReactiveNode instance.

Keep this getter deterministic. Do not start subscriptions, perform network work, or mutate state here. Use ReactiveNode.onObserved, ReactiveNode.onUnobserved, and ReactiveNode.onChanged for lifecycle work.

The returned array may change length or ordering while the node is observed. Retree treats added, removed, or reordered entries as invalidation and refreshes subscriptions. Use null when you want an inactive slot to keep its position, but it is not required for correctness.

Example

class ProjectSummary extends ReactiveNode {
    public tasks: { done: boolean }[] = [];

    get doneCount() {
        return this.tasks.filter((task) => task.done).length;
    }

    get dependencies() {
        return [this.dependency(this.tasks, [this.doneCount])];
    }
}

Returns

never[]

Overrides#

ReactiveNode.dependencies

Methods#

dependency()#

Call Signature#

dependency<TNode>(node, comparisons?): IReactiveDependency<TNode>;

Defined in: ReactiveNode.ts:593

Creates a new IReactiveDependency instance.

Type Parameters

Parameters

Returns

IReactiveDependency<TNode>

dependency object.

Remarks

Use this inside the ReactiveNode.dependencies getter or an @select dependency selector when one slot needs explicit comparison cells. If node is a Retree-managed object, it is observed with nodeChanged. If node is a primitive or unproxied value, Retree treats it as a comparison-only dependency.

Comparison cells should be deterministic. If their length/order changes, Retree treats that as invalidation and emits for this node. If no comparisons are provided, every nodeChanged event from the dependency emits for this node.

Example

get dependencies() {
    return [
        this.authStore,
        this.authStore.session?.userId,
        this.dependency(this.selectedProject ?? null, [this.projectId]),
    ];
}

Inherited from

ReactiveNode.dependency

Call Signature#

dependency<TValue>(value): IReactiveDependency;

Defined in: ReactiveNode.ts:597

Creates a new IReactiveDependency instance.

Type Parameters

Parameters

Returns

IReactiveDependency

dependency object.

Remarks

Use this inside the ReactiveNode.dependencies getter or an @select dependency selector when one slot needs explicit comparison cells. If node is a Retree-managed object, it is observed with nodeChanged. If node is a primitive or unproxied value, Retree treats it as a comparison-only dependency.

Comparison cells should be deterministic. If their length/order changes, Retree treats that as invalidation and emits for this node. If no comparisons are provided, every nodeChanged event from the dependency emits for this node.

Example

get dependencies() {
    return [
        this.authStore,
        this.authStore.session?.userId,
        this.dependency(this.selectedProject ?? null, [this.projectId]),
    ];
}

Inherited from

ReactiveNode.dependency

link()#

link<TNode>(node): RetreeLink<TNode>;

Defined in: ReactiveNode.ts:341

Create a reactive pointer to an existing Retree-managed node.

Type Parameters#

Parameters#

Returns#

RetreeLink<TNode>

A Retree-managed RetreeLink whose current points at node.

Remarks#

This is a convenience wrapper around Retree.link. Use it when a ReactiveNode method needs to return or store a pointer to a node owned elsewhere without reparenting that node.

Do not use link when ownership should move; use Retree.move or ReactiveNode.moveTo. Do not use it when two locations need independent state; use Retree.clone.

Example#

class EditorState extends ReactiveNode {
    public selected = null as RetreeLink<Task> | null;

    get dependencies() {
        return [];
    }

    public select(task: Task) {
        this.selected = this.link(task);
    }
}

Inherited from#

ReactiveNode.link

memo()#

Call Signature#

protected memo<T>(fn, comparisons?): T;

Defined in: ReactiveNode.ts:705

Memoize the result of fn, scoped to this ReactiveNode instance.

Type Parameters

Parameters

Returns

T

Remarks

Two forms:

• Keyless (inside a getter): this.memo(fn, deps?) — derives the cache key from the active getter's property name. Throws if called outside a getter or more than once in the same getter.
• Explicit key: this.memo(key, fn, deps?) — works anywhere; required when stacking multiple memo cells in one getter, or memoizing inside a method.

Cache semantics for comparisons:

• Omitted/undefined: run fn under automatic dependency trapping and recompute when one of the trapped reads changes.
• []: compute once and cache forever for this instance.
• [a, b, ...]: recompute when any cell shallow-changes using Object.is. Tree-node cells are compared by their latest reproxy identity, so passing this.list correctly invalidates when list mutates.

memo is a cache, not a subscription. It does not emit nodeChanged or trigger React renders by itself. Pair it with dependencies, Retree.select, or useSelect when you also need notification behavior.

Example

class ListFilter extends ReactiveNode {
   list: Card[] = [];
   searchText = "";
   // Keyless form
   get filteredList() {
       return this.memo(
           () => this.list.filter((c) => c.text === this.searchText),
           [this.list, this.searchText]
       );
   }
   // Explicit-key form (e.g. when stacking two memos in one getter)
   get pair() {
       const a = this.memo("a", () => expensiveA(), [this.list]);
       const b = this.memo("b", () => expensiveB(), [this.searchText]);
       return { a, b };
   }
   get dependencies() { return [this.dependency(this.list)]; }
}

Inherited from

ReactiveNode.memo

Call Signature#

protected memo<T>(
   key, 
   fn, 
   comparisons?): T;

Defined in: ReactiveNode.ts:706

Memoize the result of fn, scoped to this ReactiveNode instance.

Type Parameters

Parameters

Returns

T

Remarks

Two forms:

• Keyless (inside a getter): this.memo(fn, deps?) — derives the cache key from the active getter's property name. Throws if called outside a getter or more than once in the same getter.
• Explicit key: this.memo(key, fn, deps?) — works anywhere; required when stacking multiple memo cells in one getter, or memoizing inside a method.

Cache semantics for comparisons:

• Omitted/undefined: run fn under automatic dependency trapping and recompute when one of the trapped reads changes.
• []: compute once and cache forever for this instance.
• [a, b, ...]: recompute when any cell shallow-changes using Object.is. Tree-node cells are compared by their latest reproxy identity, so passing this.list correctly invalidates when list mutates.

memo is a cache, not a subscription. It does not emit nodeChanged or trigger React renders by itself. Pair it with dependencies, Retree.select, or useSelect when you also need notification behavior.

Example

class ListFilter extends ReactiveNode {
   list: Card[] = [];
   searchText = "";
   // Keyless form
   get filteredList() {
       return this.memo(
           () => this.list.filter((c) => c.text === this.searchText),
           [this.list, this.searchText]
       );
   }
   // Explicit-key form (e.g. when stacking two memos in one getter)
   get pair() {
       const a = this.memo("a", () => expensiveA(), [this.list]);
       const b = this.memo("b", () => expensiveB(), [this.searchText]);
       return { a, b };
   }
   get dependencies() { return [this.dependency(this.list)]; }
}

Inherited from

ReactiveNode.memo

moveTo()#

Call Signature#

moveTo<TValue>(destination, key?): this;

Defined in: ReactiveNode.ts:292

Move this node to a new structural parent.

Type Parameters

Parameters

Returns

this

The latest reproxy for this node after it moves.

Remarks

This is a convenience wrapper around Retree.move. Use it from instance methods when a node should transfer ownership to another Retree-managed array, map, set, or object.

Do not call moveTo on a root node; roots have no parent to remove from. Do not manually remove the node from its current parent before moving.

Example

class Task extends ReactiveNode {
    public title = "";

    get dependencies() {
        return [];
    }

    public complete(done: Task[]) {
        this.moveTo(done); // same as Retree.move(this, done)
    }
}

Inherited from

ReactiveNode.moveTo

Call Signature#

moveTo<TKey, TValue>(destination, key): this;

Defined in: ReactiveNode.ts:296

Move this node to a new structural parent.

Type Parameters

Parameters

Returns

this

The latest reproxy for this node after it moves.

Remarks

This is a convenience wrapper around Retree.move. Use it from instance methods when a node should transfer ownership to another Retree-managed array, map, set, or object.

Do not call moveTo on a root node; roots have no parent to remove from. Do not manually remove the node from its current parent before moving.

Example

class Task extends ReactiveNode {
    public title = "";

    get dependencies() {
        return [];
    }

    public complete(done: Task[]) {
        this.moveTo(done); // same as Retree.move(this, done)
    }
}

Inherited from

ReactiveNode.moveTo

Call Signature#

moveTo<TValue>(destination): this;

Defined in: ReactiveNode.ts:300

Move this node to a new structural parent.

Type Parameters

Parameters

Returns

this

The latest reproxy for this node after it moves.

Remarks

This is a convenience wrapper around Retree.move. Use it from instance methods when a node should transfer ownership to another Retree-managed array, map, set, or object.

Do not call moveTo on a root node; roots have no parent to remove from. Do not manually remove the node from its current parent before moving.

Example

class Task extends ReactiveNode {
    public title = "";

    get dependencies() {
        return [];
    }

    public complete(done: Task[]) {
        this.moveTo(done); // same as Retree.move(this, done)
    }
}

Inherited from

ReactiveNode.moveTo

Call Signature#

moveTo<TDestination>(destination, key): this;

Defined in: ReactiveNode.ts:303

Move this node to a new structural parent.

Type Parameters

Parameters

Returns

this

The latest reproxy for this node after it moves.

Remarks

This is a convenience wrapper around Retree.move. Use it from instance methods when a node should transfer ownership to another Retree-managed array, map, set, or object.

Do not call moveTo on a root node; roots have no parent to remove from. Do not manually remove the node from its current parent before moving.

Example

class Task extends ReactiveNode {
    public title = "";

    get dependencies() {
        return [];
    }

    public complete(done: Task[]) {
        this.moveTo(done); // same as Retree.move(this, done)
    }
}

Inherited from

ReactiveNode.moveTo

onChanged()#

protected onChanged(_changes): void;

Defined in: ReactiveNode.ts:562

Runs after this ReactiveNode receives a fresh reproxy.

Parameters#

Returns#

void

Remarks#

Override this when a node needs to synchronize derived state only after a real Retree change. Retree runs this before nodeChanged / treeChanged listeners flush. If no transaction is already active, Retree starts one so state updates made here are batched with the reproxy that triggered the effect.

Use this for small synchronization writes that should happen only after Retree has confirmed a real change. Avoid writing unconditionally here; guard against loops by checking whether the derived value actually changed.

Example#

class SearchState extends ReactiveNode {
    public query = "";
    public normalizedQuery = "";

    get dependencies() {
        return [];
    }

    protected onChanged() {
        const next = this.query.trim().toLowerCase();
        if (this.normalizedQuery !== next) {
            this.normalizedQuery = next;
        }
    }
}

Inherited from#

ReactiveNode.onChanged

onObserved()#

protected onObserved(): void;

Defined in: ReactiveNode.ts:508

Runs when this ReactiveNode gets its first active nodeChanged or treeChanged observer.

Returns#

void

Remarks#

Override this for work that requires the proxied instance, such as starting external subscriptions that write back into Retree state.

Keep setup idempotent. Retree calls this when the first active nodeChanged or treeChanged listener starts observing the node, not when the node is constructed.

Example#

class LiveValue extends ReactiveNode {
    public value = "";
    @ignore private unsubscribe: (() => void) | null = null;

    get dependencies() {
        return [];
    }

    protected onObserved() {
        this.unsubscribe = subscribe((value) => {
            this.value = value; // ✅ emits through Retree
        });
    }
}

Inherited from#

ReactiveNode.onObserved

onUnobserved()#

protected onUnobserved(): void;

Defined in: ReactiveNode.ts:527

Runs when this ReactiveNode loses its last active nodeChanged or treeChanged observer.

Returns#

void

Remarks#

Use this to clean up resources created in ReactiveNode.onObserved. Do not rely on it as a destructor for unobserved nodes; it only runs after observation had started.

Example#

protected onUnobserved() {
    this.unsubscribe?.();
    this.unsubscribe = null;
}

Inherited from#

ReactiveNode.onUnobserved

peekInto()#

peekInto<TResult>(fn): TResult;

Defined in: ReactiveNode.ts:442

Run a read-only query against this node's raw object at native speed, then resolve the result back to its Retree-managed node when one exists.

Type Parameters#

Parameters#

Returns#

TResult

The callback result, resolved to its managed node when one exists.

Remarks#

This is a convenience wrapper around Retree.peekInto for this. The callback receives the raw object behind this node (ReactiveNode.raw), so reads inside it skip proxy traps and are not tracked as dependencies. If the returned value is an object that belongs to a Retree tree, the latest managed node (reproxy or base proxy) is returned instead; primitives and unmanaged objects are returned as-is.

Only the returned value itself is resolved. Containers built inside the callback (for example filter results) are returned unchanged, with raw elements. Children that have never been read through the managed tree have no proxy yet and resolve to their raw value; traverse the path once, or use prepareTree / autoPrepare, when a managed result is required.

Example#

class TaskList extends ReactiveNode {
    public tasks: Task[] = [];

    get dependencies() {
        return [this.dependency(this.tasks)];
    }

    public findTask(id: string): Task | undefined {
        // Scans raw at native speed; returns the managed task node.
        return this.peekInto((raw) =>
            raw.tasks.find((task) => task.id === id)
        );
    }
}

Inherited from#

ReactiveNode.peekInto

prepareTree()#

prepareTree(options?): void;

Defined in: ReactiveNode.ts:649

Prepare lazy Retree child proxies below this ReactiveNode.

Parameters#

Returns#

void

Remarks#

Retree lazily proxies plain object and array fields on ReactiveNodes. Call this when an app wants to pay that first-touch cost during a controlled phase, such as while showing a loading spinner. This walks only own data properties, so computed getters like dependencies are not evaluated or cached as child nodes. Fields marked with @ignore are skipped.

Do not call this for every render. Call it once during setup, loading, or before a known interaction that will traverse a large subtree.

Example#

class LargeNode extends ReactiveNode {
    public sections = [{ title: "Intro", cards: [] }];

    get dependencies() {
        return [];
    }
}

const node = Retree.root(new LargeNode());
node.prepareTree({ depth: 1 });

Inherited from#

ReactiveNode.prepareTree

raw()#

raw(): this;

Defined in: ReactiveNode.ts:378

Get the raw, unproxied object behind this node for read-only, non-reactive access.

Returns#

this

The raw object behind this node.

Remarks#

This is a convenience wrapper around Retree.raw for this. Reads on the returned object skip proxy traps entirely, so algorithms that scan large collections owned by this node can run at native speed.

Treat the result as read-only: direct mutations skip Retree change emission. Reads are invisible to reactivity, including this node's own auto-trapped @memo / @select dependency collection. Throws when the node is not yet Retree-managed (for example inside the constructor, before Retree.root(...) or tree attachment).

Example#

class Leaderboard extends ReactiveNode {
    public scores: number[] = [];

    get dependencies() {
        return [this.dependency(this.scores)];
    }

    get total() {
        // Raw scan; reactivity comes from `dependencies`.
        return this.raw().scores.reduce((sum, s) => sum + s, 0);
    }
}

Inherited from#

ReactiveNode.raw

untracked()#

untracked<T>(fn): T;

Defined in: ReactiveNode.ts:394

Run a synchronous function with Retree dependency tracking paused.

Type Parameters#

Parameters#

Returns#

T

The function's return value.

Remarks#

This is a convenience wrapper around Retree.untracked. Use it inside auto-trapped @memo, @fnMemo, and @select bodies when bulk reads should not become dependencies. Reads still go through Retree proxies; writes still emit normally.

Inherited from#

ReactiveNode.untracked