es6-callback-manager

ES6 CallbackManager

A class for managing asynchronous callbacks in JavaScript

Installation

npm install es6-callback-manager --save

Transpiling

This module uses ECMAScript 2015 syntax (more widely known as ES6). If you need to use this module in an environment that only supports ES5 (such as a browser or an older version of Node.js), you'll need to transpile it from ES6 to ES5 using a transpiler such as Babel.

API Reference

CallbackManager

• CallbackManager
  • new CallbackManager(callback)
  • .callback : function
  • .registerCallback() ⇒ function
  • .getCount() ⇒ number
  • .abort() ⇒ void

---

new CallbackManager(callback)

Creates a new CallbackManager.

Param	Type	Description
callback	function	The callback to invoke once all intermediary callbacks have been invoked. Is invoked immediately if one of the callbacks is called with an Error as the first argument and is passed the Error object as the first argument.

Example

var CallbackManager = require('es6-callback-manager');
var cbManager = new CallbackManager(function(err) {
  if (err) throw err;
  console.log('Done!');
});
setTimeout(cbManager.registerCallback(), 200);
setTimeout(cbManager.registerCallback(), 100);
setTimeout(cbManager.registerCallback(), 300);

---

callbackManager.callback : function

The callback passed to the constructor. Is read-only.

---

callbackManager.registerCallback() ⇒ function

Returns an intermediary callback and increases the number of callbacks to wait for until the original callback will be invoked.

Returns: function - An intermediary callback that, when invoked, decreases the number of callbacks to wait for. If it is the last callback being waited on, it invokes the original callback. If it is called with an Error as the first argument, it invokes the original callback immediately with the Error.

Example

var cbManager = new CallbackManager(callback);
process.nextTick(cbManager.registerCallback());

var cb = cbManager.registerCallback();
cb('error'); // Does nothing since a string is not an Error object

var error = new Error();
cb = cbManager.registerCallback();
cb(error); // Stops waiting for other callbacks and calls callback(error)

---

callbackManager.getCount() ⇒ number

Returns the number of intermediary callbacks currently being waited on.

Example

var cbManager = new CallbackManager(function() {
  cbManager.getCount(); // -> 0
});
process.nextTick(cbManager.registerCallback());
cbManager.getCount(); // -> 1
process.nextTick(cbManager.registerCallback());
cbManager.getCount(); // -> 2

---

callbackManager.abort() ⇒ void

Aborts the callback sequence, preventing the original callback from being invoked once all intermediary callbacks have been invoked.

Example

var cbManager = new CallbackManager(function() {
  console.log('This is never called');
});
setTimeout(cbManager.registerCallback(), 100);
setTimeout(function() {
  cbManager.abort();
}, 50);

---