/cjs-noticeboard

Self-Logging Pubsub with Built-In Cache

Primary LanguageJavaScript

CJS-NOTICEBOARD

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WHAT IS A NOTICEBOARD?

A Noticeboard is just the Pub-Sub pattern with a twist: most-recently published values are cached and accessible by future subscribers.

HOW TO USE IT

Install

	npm install cjs-noticeboard

Basic Use

Create New Noticeboard

	var Noticeboard = require('cjs-noticeboard'),
		board = new Noticeboard();

Subscribe to Notice

	
	var notice = 'new-user',
		watcher = 'greet-new-users';

	board.watch( notice, watcher, function( message ){

		console.log( "Hello " + message.notice.username + "!" );
	});

Publish to Notice Watchers

	board.notify( 'new-user', { username: 'akamaozu' });

Stop Subscribing to a Notice

	
	board.ignore( 'new-user', 'greet-new-users' )

Advanced Use

Unsubscribe Immediately After Responding to a Notice

	
	board.once( 'new-user', 'identify-first-user-only', function( message ){

		console.log( "First User: " + message.notice.username );
	});

Use Previous Notice and Subscribe to Future Notices

	
	board.watch( 'window-size', 'log-window-size', function( message ){

		console.log( "w: " + message.notice.width  " | h: " + message.notice.height );

	}, { useCache: true });

Enable Noticeboard Log Feature

	var Noticeboard = require('cjs-noticeboard'),
		board = new Noticeboard({ logging: true });

	// or

	board.settings.logging = true;

Enable Noticeboard Internal Operation Logging

Note: Noticeboard must have settings logging set to true

	var Noticeboard = require('cjs-noticeboard'),
		board = new Noticeboard({ logOps: true });

	// or

	board.settings.logOps = true;

Handle Noticeboard Logs

	
	board.watch( 'log-entry', 'process-board-logs', function( message ){

		var entry = message.notice;

		console.log.apply( console, entry );
	});

API

new Noticeboard(settings)

Create a new Noticeboard Instance. Behavior can be configured with settings.

  • Is a Function
  • Arguments
    • settings
      • type: Object {}
      • required: false
      • props:
        • logging
          • type: Boolean (true or false)
          • required: false
          • desc: Determines if the Noticeboard will notify subscribers of log-entry.
        • logOps
          • type: Boolean (true or false)
          • required: false
          • desc: Determines if the Noticeboard will publish notices about its internal operations to log-entry watchers.

Noticeboard.notify(notice, message, source)

Triggers the callback in every watcher of the specified notice. If there is a non-null message, the notification will be cached. The source is for attribution / debugging purposes.

  • Is a Function
  • Arguments
    • notice
      • type: String
      • required: true
    • message
      • type: Any
      • required: false
      • gotchas:
        1. notifications with a message will automatically be cached.
        2. notifications without a message will not be cached.
        3. notifications with the message object null will not be cached.
    • source
      • type: String
      • required: false

Noticeboard.watch(notice, watcher, callback, options)

Adds a watcher to the list of callbacks to execute when a notice is sent out. The execution context and parameters of the callback can be modified via options.

  • Is a Function
  • Arguments
    • notice
      • type: String
      • required: true
    • watcher
      • type: String
      • required: true
    • callback
      • type: Function
      • required: true
      • arguments passed: Object {}
      • arguments props:
        • notice
          • description: message passed from Noticeboard.notify
        • watcher
          • description: message passed from Noticeboard.watch
    • options

      • type: Object {}

      • required: false

      • props:

      • message

        • type: Any
        • required: false
        • description: Passed to callback on execution. accessible inside callback as arguments[0].watcher

      • useCache

        • type: Boolean (true or false)
        • required: false
        • description: Set to true if its okay to autofire the callback if the notification has been previously cached

      • once

        • type: Boolean (true or false)
        • required: false
        • description: Set to true if you want this watcher to autoignore the notice immediately after its callback.

Noticeboard.ignore(notice, watcher)

Remove a watcher from the list of callbacks to execute when this notice is sent out.

  • Is a Function
  • Arguments
    • notice
      • type: String
      • required: true
    • watcher
    • type: String
    • required: true

Noticeboard.once(notice, watcher, callback, options)

A simple wrapper around Noticeboard.watch that calls Noticeboard.ignore as soon as its callback is executed. See Noticeboard.watch for details this function's parameters.

Noticeboard.log()

Designed to simulate the browser's console.log, this function will notify all watchers of log-entry and pass its arguments object as the message.

For instance, this is equivalent to calling console.log, with the added benefit of not crashing if the browser doesn't have console. That and your log can be piped to other parts of your app.

Noticeboard.watch('log-entry', 'browser-console', function(msg){
	if(!console || typeof console.log !== "function"){ return; }

	console.log.apply(console, msg.notice);
}

With the above watcher, the snippet below is now a superior version of console.log.

Noticeboard.log("testing", {isTest: true}, [1,2,3], function(){})

CONTACT ME

Hop on the Noticeboard Train!

You're waiting for a train
A train that will take you far away
You know where you hope this train will take you
But you don't know for sure
Yet it doesn't matter
Because we'll be together

-- Mal (Inception, 2010)