tessl/npm-rsvp

A lightweight library that provides tools for organizing asynchronous code

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Files

RSVP.js

Name: tessl/npm-rsvp
Author: tessl

RSVP.js provides simple tools for organizing asynchronous code. It is a lightweight implementation of Promises/A+ specification that works in both Node.js and browsers (IE9+), bringing additional utilities beyond the standard ES6 Promise API.

Package Information

Package Name: rsvp
Package Type: npm
Language: JavaScript (ES5 compatible)
Installation: npm install rsvp

Core Imports

import RSVP from "rsvp";
import { Promise, all, hash, resolve, reject } from "rsvp";

For CommonJS:

var RSVP = require("rsvp");
var Promise = RSVP.Promise;

For browsers via CDN:

<script src="https://cdn.jsdelivr.net/npm/rsvp@4/dist/rsvp.min.js"></script>

Basic Usage

import { Promise, all, hash, resolve } from "rsvp";

// Create a promise
const promise = new Promise(function(resolve, reject) {
  // async operation
  setTimeout(() => resolve("Success!"), 1000);
});

promise.then(function(value) {
  console.log(value); // "Success!"
}).catch(function(error) {
  console.error(error);
});

// Wait for multiple promises
all([
  resolve(1),
  resolve(2),
  resolve(3)
]).then(function(values) {
  console.log(values); // [1, 2, 3]
});

// Work with object of promises
hash({
  users: fetchUsers(),
  posts: fetchPosts()
}).then(function(results) {
  console.log(results.users);
  console.log(results.posts);
});

Architecture

RSVP.js is built around several key components:

Promise Class: ES6-compliant Promise implementation with additional methods
Array Utilities: Functions for working with arrays of promises (all, allSettled, race, map, filter)
Object Utilities: Functions for working with objects containing promises (hash, hashSettled)
Node.js Integration: Utilities for converting callback-based functions to promises (denodeify)
Configuration System: Global configuration and instrumentation capabilities
Event System: EventTarget implementation for custom events and promise instrumentation
Async Scheduling: Cross-platform async scheduling using the best available method

Capabilities

Promise Class

Core Promise implementation following Promises/A+ specification with additional methods like finally.

class Promise {
  constructor(resolver: Function, label?: string);
  then(onFulfillment?: Function, onRejection?: Function, label?: string): Promise;
  catch(onRejection: Function, label?: string): Promise;
  finally(callback: Function, label?: string): Promise;
  
  static all(array: Array, label?: string): Promise;
  static race(array: Array, label?: string): Promise;
  static resolve(value?: any, label?: string): Promise;
  static reject(reason?: any, label?: string): Promise;
}

Promise Class

Array Promise Utilities

Functions for working with arrays of promises including parallel execution, racing, transformation, and filtering.

function all(array: Array, label?: string): Promise;
function allSettled(entries: Array, label?: string): Promise;
function race(array: Array, label?: string): Promise;
function map(promises: Array, mapFn: Function, label?: string): Promise;
function filter(promises: Array, filterFn: Function, label?: string): Promise;

Array Utilities

Object Promise Utilities

Functions for working with objects containing promises, useful for handling named async operations.

function hash(object: Object, label?: string): Promise;
function hashSettled(object: Object, label?: string): Promise;

Object Utilities

Node.js Integration

Convert Node.js callback-style functions to promise-returning functions for better async composition.

function denodeify(nodeFunc: Function, options?: boolean | Array): Function;

Node.js Integration

Configuration and Events

Global configuration system and event handling for instrumentation and debugging.

function configure(name: string, value?: any): any;
function on(...arguments): void;
function off(...arguments): void;

const EventTarget: {
  mixin(object: Object): Object;
  on(eventName: string, callback: Function): void;
  off(eventName: string, callback?: Function): void;
  trigger(eventName: string, options?: any, label?: string): void;
};

Configuration and Events

Utility Functions

Additional utility functions for promise creation, error handling, and async scheduling.

function resolve(value?: any, label?: string): Promise;
function reject(reason?: any, label?: string): Promise;
function defer(label?: string): Object;
function rethrow(reason: any): void;
function asap(callback: Function, arg?: any): void;
function async(callback: Function, arg?: any): void;

Utility Functions

Types

interface PromiseState {
  state: 'fulfilled' | 'rejected';
  value?: any;
  reason?: any;
}

interface DeferredObject {
  promise: Promise;
  resolve: Function;
  reject: Function;
}