method AsyncLocalStorage.snapshot
Unstable
Usage in Deno
import { AsyncLocalStorage } from "node:async_hooks";
AsyncLocalStorage.snapshot(): <R,TArgs extends any[],>(fn: (...args: TArgs) => R,...args: TArgs,) => R
Captures the current execution context and returns a function that accepts a function as an argument. Whenever the returned function is called, it calls the function passed to it within the captured context.
const asyncLocalStorage = new AsyncLocalStorage();
const runInAsyncScope = asyncLocalStorage.run(123, () => AsyncLocalStorage.snapshot());
const result = asyncLocalStorage.run(321, () => runInAsyncScope(() => asyncLocalStorage.getStore()));
console.log(result); // returns 123
AsyncLocalStorage.snapshot() can replace the use of AsyncResource for simple async context tracking purposes, for example:
class Foo {
#runInAsyncScope = AsyncLocalStorage.snapshot();
get() { return this.#runInAsyncScope(() => asyncLocalStorage.getStore()); }
}
const foo = asyncLocalStorage.run(123, () => new Foo());
console.log(asyncLocalStorage.run(321, () => foo.get())); // returns 123
<R,TArgs extends any[],>(fn: (...args: TArgs) => R,...args: TArgs,) => R
A new function with the signature (fn: (...args) : R, ...args) : R.