AwaitQueue

JavaScript utility to enqueue asynchronous tasks and run them sequentially one after another. For Node.js and the browser.

Installation

$ npm install awaitqueue

Usage

• In ES6:

import {
  AwaitQueue,
  AwaitQueueTask,
  AwaitQueueTaskDump,
  AwaitQueueStoppedError,
  AwaitQueueRemovedTaskError
} from 'awaitqueue';

• In CommonJS:

const { 
  AwaitQueue,
  AwaitQueueTask,
  AwaitQueueTaskDump,
  AwaitQueueStoppedError,
  AwaitQueueRemovedTaskError
} = require('awaitqueue');

Types

type AwaitQueueTask

type AwaitQueueTask<T> = () => (T | PromiseLike<T>);

TypeScript type representing a function that returns a value T or a Promise that resolves with T.

type AwaitQueueTaskDump

type AwaitQueueTaskDump =
{
  idx: number;
  task: AwaitQueueTask<unknown>;
  name?: string;
  enqueuedTime: number;
  executionTime: number;
};

TypeScript type representing an item in the array returned by the awaitQueue.dump() method.

• idx: Index of the pending task in the queue (0 means the task being processed now).
• task: The function to be executed.
• name: The name of the given function (if any) or the name argument given to awaitQueue.push() method (if any).
• enqueuedTime: Time in milliseconds since the task was enqueued, this is, since awaitQueue.push() was called until its execution started or until now if not yet started.
• executionTime: Time in milliseconds since the task execution started (or 0 if not yet started).

API

new AwaitQueue()

Creates an AwaitQueue instance.

awaitQueue.size: number

Number of enqueued pending tasks.

async awaitQueue.push(task: AwaitQueueTask<T>, name?: string): Promise<T>

Accepts a task as argument and enqueues it after pending tasks. Once processed, the push() method resolves (or rejects) with the result returned by the given task.

• @param task: Asynchronous or asynchronous function.
• @param name: Optional task name (useful for awaitQueue.dump() method).

awaitQueue.stop(): void

Make pending tasks reject with an instance of AwaitQueueStoppedError. The AwaitQueue instance is still usable for future tasks added via push() method.

awaitQueue.remove(taskIdx: number): void

Removes the pending task with given index. The task is rejected with an instance of AwaitQueueRemovedTaskError.

• @param taskIdx: Index of the pending task to be removed.

awaitQueue.dump(): AwaitQueueTaskDump[]

Returns an array with information about pending tasks in the queue. See the AwaitQueueTaskDump type above.

Usage example

See test.ts file.

Author

• Iñaki Baz Castillo [website|github]

License

ISC