observable

Allows objects to watch for changes to an object via Proxy. observable uses harmony-reflect for Proxy support. Requires the --harmony_proxies flag to be set on the nodejs executable

observable is an EventEmitter.

Installation

Install with npm

npm install observable

Usage

observable = require "observable"

Example

Clone an existing object

obj = { a : 1 }
o2 = observable obj
assert.equal o2.a, 1
assert.equal o2.b, undefined

Emit change events

# Clone an existing object 
obj = { a : 1 }
o2 = observable obj
 
# Listen for "changed" events 
o2.on "changed", ( name, old, value ) ->
  assert.equal name, "a"
  assert.equal value, 2
 
# Modify a property on our observable object 
o2.a = 2

Nested Keys

o2 = observable {}
o2.a = {} # o2.a is automatically converted to an observable object 
 
o2.on "changed", ( name, old, value ) ->
  assert.equal name, "a.b"
  assert.equal value, 1
 
# Modify a nested property 
o2.a.b = 1

Delete keys

obj = observable { a : { b : 2 } }
obj.on "deleted", ( name ) ->
  assert.equal name, 'a'
 
delete obj.a

observable (obj)

• obj {optional Object} An initial object which is cloned (immutable).
• Returns a Proxy to the cloned object

Clones an object and returns a Proxy to the cloned object. Changes to the cloned object are not reflected on the original.

Objects assigned to keys of an observable object are themselves converted to observable objects.

Events

changed (name, old, value)

• name Property name with path, if nested.
• old The previous value
• value The new value

Emitted when a (possibly nested) value of a an observable object is modified.

deleted (name)

• name Property name with path, if nested.

Emitted when a property is deleted