@azure/abort-controller

What is @azure/abort-controller?

The @azure/abort-controller npm package provides a way to use AbortController and AbortSignal, which are interfaces for abortable operations, in the Azure SDKs. These are particularly useful for cancelling asynchronous operations in JavaScript, such as network requests or long-running processes.

What are @azure/abort-controller's main functionalities?

Creating an AbortController and AbortSignal

This feature allows you to create an instance of AbortController and retrieve its AbortSignal. The signal can then be passed to operations that support cancellation.

const { AbortController } = require('@azure/abort-controller');
const controller = new AbortController();
const signal = controller.signal;

Aborting an operation

This feature enables you to abort an operation by calling the `abort` method on the controller. Any operation listening to the associated signal will be cancelled.

controller.abort();

Listening for an abort signal

This feature allows you to listen for an abort event on the AbortSignal. This is useful for performing cleanup or rollback actions when an operation is cancelled.

signal.addEventListener('abort', () => {
  console.log('Operation aborted!');
});

Other packages similar to @azure/abort-controller

abort-controller

The 'abort-controller' package provides a similar API for creating abortable operations using AbortController and AbortSignal. It is a polyfill for the AbortController interface that works in both web browsers and Node.js environments. Compared to @azure/abort-controller, it is not specific to Azure SDKs and can be used in a wider range of applications.

README

Azure Abort Controller client library for JavaScript

The @azure/abort-controller package provides AbortController and AbortSignal classes. These classes are compatible with the AbortController built into modern browsers and the AbortSignal used by fetch. Use the AbortController class to create an instance of the AbortSignal class that can be used to cancel an operation in an Azure SDK that accept a parameter of type AbortSignalLike.

Key links:

• Source code
• Package (npm)
• API Reference Documentation

Getting started

Installation

Install this library using npm as follows

npm install @azure/abort-controller

Key Concepts

Use the AbortController to create an AbortSignal which can then be passed to Azure SDK operations to cancel pending work. The AbortSignal can be accessed via the signal property on an instantiated AbortController. An AbortSignal can also be returned directly from a static method, e.g. AbortController.timeout(100). that is cancelled after 100 milliseconds.

Calling abort() on the instantiated AbortController invokes the registered abort event listeners on the associated AbortSignal. Any subsequent calls to abort() on the same controller will have no effect.

The AbortSignal.none static property returns an AbortSignal that can not be aborted.

Multiple instances of an AbortSignal can be linked so that calling abort() on the parent signal, aborts all linked signals. This linkage is one-way, meaning that a parent signal can affect a linked signal, but not the other way around. To link AbortSignals together, pass in the parent signals to the AbortController constructor.

Examples

The below examples assume that doAsyncWork is a function that takes a bag of properties, one of which is of the abort signal.

Example 1 - basic usage

import { AbortController } from "@azure/abort-controller";

const controller = new AbortController();
doAsyncWork({ abortSignal: controller.signal });

// at some point later
controller.abort();

Example 2 - Aborting with timeout

import { AbortController } from "@azure/abort-controller";

const signal = AbortController.timeout(1000);
doAsyncWork({ abortSignal: signal });

Example 3 - Aborting sub-tasks

import { AbortController } from "@azure/abort-controller";

const allTasksController = new AbortController();

const subTask1 = new AbortController(allTasksController.signal);
const subtask2 = new AbortController(allTasksController.signal);

allTasksController.abort(); // aborts allTasksSignal, subTask1, subTask2
subTask1.abort(); // aborts only subTask1

Example 4 - Aborting with parent signal or timeout

import { AbortController } from "@azure/abort-controller";

const allTasksController = new AbortController();

// create a subtask controller that can be aborted manually,
// or when either the parent task aborts or the timeout is reached.
const subTask = new AbortController(allTasksController.signal, AbortController.timeout(100));

allTasksController.abort(); // aborts allTasksSignal, subTask
subTask.abort(); // aborts only subTask

Next steps

You can build and run the tests locally by executing rushx test. Explore the test folder to see advanced usage and behavior of the public classes.

Troubleshooting

If you run into issues while using this library, please feel free to file an issue.

Contributing

If you'd like to contribute to this library, please read the contributing guide to learn more about how to build and test the code.