emitting-map

A map that emits events when it is updated. The events are simple and ensure that you can easily keep views, other stores, and whatever else in sync with it.

Example

var EmittingMap = require('emitting-map');

// Initial state can be passed during construction, or it will be empty
var map = new EmittingMap({some: 'values', and: 'keys'}, {deleteOnSet: true});

// The handler will be called once for each event required to bring a new listener
// up to date with the current state of the map
counter.onChange(function(type, key, value) {
	switch(type) {
	case 'set':
		chatroom.addUser(value);
		break;
	case 'delete':
		chatroom.removeUser(value);
	}
});

// The handler will be called again with this new update
list.delete('some');

Methods

• constructor([map, options]) - map may be a Map instance, or a plain object. options should be an object with some properties:
  • deleteOnSet=false - If true, whenever an existing key is set first delete the key and emit the associated delete event.
• .get(key) - Returns the value stored in key
• .set(key, value) - Adds key/value pair to the map
• .delete(key) - Removes key from the map
• .onChange(fn) - Registers fn as a handler that will be called whenever the map is updated. Also returns a function that will unregister your callback when called.