* `fn` {Function} The function to bind to the current execution context.

* Returns: {Function} A new function that calls `fn` within the captured

execution context.

Binds the given function to the current execution context.

* Returns: {Function} A new function with the signature

`(fn: (...args) : R, ...args) : 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

static bind(fn) {

return AsyncResource.bind(fn);

}

static snapshot() {

return AsyncLocalStorage.bind((cb, ...args) => cb(...args));

}

const common = require('../common');

const assert = require('assert');

const { AsyncLocalStorage } = require('async_hooks');

[1, false, '', {}, []].forEach((i) => {

assert.throws(() => AsyncLocalStorage.bind(i), {

code: 'ERR_INVALID_ARG_TYPE'

});

const fn = common.mustCall(AsyncLocalStorage.bind(() => 123));

assert.strictEqual(fn(), 123);

const fn2 = AsyncLocalStorage.bind(common.mustCall((arg) => assert.strictEqual(arg, 'test')));

const common = require('../common');

const { strictEqual } = require('assert');

const { AsyncLocalStorage } = require('async_hooks');

const asyncLocalStorage = new AsyncLocalStorage();

const runInAsyncScope =

asyncLocalStorage.run(123, common.mustCall(() => AsyncLocalStorage.snapshot()));

const result =

asyncLocalStorage.run(321, common.mustCall(() => {

return runInAsyncScope(() => {

return asyncLocalStorage.getStore();

});

}));

strictEqual(result, 123);