A smart and efficient javascript object observer, ideal for batching DOM updates (~1kb)

Installation

Via npm

$ npm i icaro -S

Script import

Via <script>

<script src='path/to/icaro.js'></script>

Via ES2015 modules

import icaro from 'icaro'

Via commonjs

const icaro = require('icaro')

Demos

• The Canvas
• The Counter
• The Stress

Performance

icaro is really fast compared to the other reactive libs because it smartly throttles all the state changes.

Usage

icaro will let you listen to all the changes happening in a javascript object or array, grouping them efficiently, and optimizing the performance of your listeners.

const obj = icaro({})

// the variable "changes" here is a Map and the function is async
obj.listen(function(changes) {
  console.log(changes.get('foo')) // 'hi'
  console.log(changes.get('bar')) // 'there'
  console.log(changes.get('baz')) // 'dude'

  // kill all the listeners
  obj.unlisten()
})

obj.foo = 'hi'
obj.bar = 'there'
obj.baz = 'dude'

icaro will also let you listen to nested objects and all the non primitive properties added to an icaro object will be automatically converted into icaro observable objects.

const obj = icaro({})

// listen only the changes happening on the root object
obj.listen(function(changes) {
})

obj.nested = {

}

obj.nested.listen(function(changes) {
  // listen only the changes of obj.nested
})

obj.nested.someVal = 'hello'

icaro is able also to listen changes in arrays. Any change to the items indexes will dispatch events.

// Here a bit of hardcore async stuff

const arr = icaro([])

// here you will get the index of the items added or who changed their position
arr.listen(function(changes) {
  console.log(changes.get('0')) // 'foo'
  console.log(changes.get('1')) // 'bar'
  // kill all the listeners this included
  arr.unlisten()

  // add a brand new listener recursively.. why not?
  arr.listen(function(changes) {
    // the change was triggered by a 'reverse' and all indexes were updated
    console.log(changes.get('0')) // 'bar'
    console.log(changes.get('1')) // 'foo'
  })

  // update all the indexes
  arr.reverse()
})

// initial dispatch
arr.push('foo')
arr.push('bar')

You can also avoid unsubscribing ("unlisten") because icaro will automatically remove event listeners when the object is about to be garbage collected.

API

Any icaro call will return a Proxy with the following api methods

icaro.listen(callback)

Listen any object or array calling the callback function asynchronously grouping all the contiguous changes via setImmediate

@returns self

icaro.unlisten(callback|null)

Unsubscribing a callback previously subscribed to the object, if no callback is provided all the previous subscriptions will be cleared

@returns self

icaro.toJSON()

Return all data contained in an icaro Proxy as JSON object

@returns Object

Support

icaro uses advanced es6 features like Proxies, WeakMaps, Maps and Symbols and it targets only modern browsers

All major evergreen browsers (Edge, Chrome, Safari, Firefox) should be supported