on-dispose

This package provides helpers for conveniently triggering dispose/asyncDispose actions using the using syntax in JavaScript/TypeScript.

Install

# If you're using npm
npm install on-dispose

# If you're using yarn
yarn add on-dispose

# If you're using pnpm
pnpm add on-dispose

Usage

A using statement in JavaScript / TypeScript will trigger the method [Symbol.dispose]() when the object goes out of scope.

An await using statement in JavaScript / TypeScript will trigger the method [Symbol.asyncDispose]() when the object goes out of scope.

Both types of using statements are similar in behaviour to a try { ... } finally { ... } statement.

on-dispose provides two helper functions onDispose and onAsyncDispose that accept an action you would like to trigger on dispose / async dispose respectively without having to define a class or object for it.

import { onDispose, onAsyncDispose } from "on-dispose";

// You can use onDispose with a synchronous action in a regular function.

const fn1 = () => {
    using _ = onDispose(() => {
        console.log("Synchronous dispose action in a synchronous function with using");
    })
}

// onDispose also works with a synchronous action in an async function.

const fn2 = async () => {
    using _ = onDispose(() => {
        console.log("Synchronous dispose action in an async function with using")
    })
}

// You can use onAsyncDispose with an asynchronous action in an async function.

const fn3 = async () => {
    await using _ = onAsyncDispose(async () => {
        console.log("Asynchronous dispose action in an async function with await using")
    })
}

// onAsyncDispose also works with a synchronous action.

const fn4 = async () => {
    await using _ = onAsyncDispose(() => {
        console.log("Synchronous dispose action in an async function with await using")
    })
}

const main = async () => {
    fn1();
    await fn2()
    await fn3()
    await fn4()
}

void main();

// Will print:
//
// Synchronous dispose action in a synchronous function with using
// Synchronous dispose action in an async function with using
// Asynchronous dispose action in an async function with await using
// Synchronous dispose action in an async function with await using

Naturally, you cannot run async dispose actions in regular / non-async functions.

onDispose returns a Disposable object and onAsyncDispose returns an AsyncDisposable object, so you can also use both with DisposableStack and AsyncDisposableStack.

License

MIT