Scope Slots

Scope slots are typed tokens for storing values on a scope and resolving them through the parent chain.

Creating Slots

Create a slot with ScopeSlot.create<T>():

import { createScope, ScopeSlot } from "@kayahr/scope";

const localeSlot = ScopeSlot.create<string>();

const root = createScope();
root.set(localeSlot, "en");

const child = createScope(root);
child.get(localeSlot);  // undefined
child.find(localeSlot); // "en"

child.set(localeSlot, "de");
child.get(localeSlot);  // "de"
child.find(localeSlot); // "de"
Copy

Slots are compared by identity, not by name.

Lookup

• scope.set(slot, value) stores a local value on one scope.
• scope.get(slot) reads only the local value from that scope.
• scope.has(slot) checks whether that scope has a local value.
• scope.delete(slot) removes only the local value from that scope.
• scope.find(slot) walks up the parent chain and returns the nearest stored value.

scope.get(...) and scope.find(...) return undefined when no value exists.

Disposal

After disposal has completed, local slot values are cleared. scope.get(...) and scope.find(...) return undefined, and scope.has(...) returns false.

Writing to a disposed scope throws a ScopeError. That includes set(...) and delete(...).