listen

listen.js

Wait for the results of multiple callbacks.

Install

npm install listen

Usage

var listen = require('listen');

var listener = listen();

var callbackA = listener();
var callbackB = listener();

/*
 * Do async stuff with callbacks.
 *
 * Callbacks follow the Node.js convention. They expect an error or null as
 * the first argument and an optional value as the second:
 *
 * Fail: callback(new Error('ouch!'));
 * Return: callback(null, 'some return value');
 */

listener.then(function (err, values) {
  /*
   * err    - 1) null if no callback err'd
   *          2) the error of the callback that err'd
   *          3) an error with name ErrorList wrapping multiple errors
   *
   * values - The non-undefined return values from all callbacks in order of
   *          callback creation
   */
});

API

listen([values])

Creates and returns a new listener. The values array with initial values is optional.

listener([timeout])

Creates a new callback associated with the listener. If the optional timeout is given, the listener errs with a TimeoutError if the callback was not invoked. Throws if called after then.

listener.then(func)

Invokes the given function once all callbacks where invoked. If none of the callbacks had errors, the first argument is null, otherwise it's an Error. The second argument is the values array in order of callback creation. Can only be called once.

listener.push(value)

Pushes a value to the internal values array. Throws if called after then.

listener.err(error)

Adds an error to the internal error list. Throws if called after then.

Run tests

make

Hacking

If you'd like to hack listen.js here is how to get started:

• npm install will setup everything you need.
• make lints the code with JSLint and runs all unit tests.
• Use can also make lint or make test individually.

Running the test cases in a browser instead of Node requires nomo.js.

• Run npm install -g nomo
• Run nomo server from within the project directory.
• Open http://localhost:4444/test in your browser.

To build a browser package containing the merged / minified scripts run make package.