observable array

gistfile1.js

var mutators = [
  'fill', 'pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'
]

function ObservableArray(onChange){
  var array = []

  array.set = set
  array.onchange = onChange

  // proxy mutator methods
  for (var i=0;i<mutators.length;i++){
    array[mutators[i]] = proxies[mutators[i]]
  }

  return array
}

function set(value){
  this.length = 0
  if (Array.isArray(value)){
    Array.prototype.push.apply(this, value);
    if (typeof target.onchange === 'function'){
      target.onchange()
    }
  }
}

var proxies = {}
for (var i=0;i<mutators.length;i++){
  var method = mutators[i]
  proxies[method] = proxyWithNotify(Array.prototype[method])
}

function proxyWithNotify(method){
  return function(args){
    var result = method.apply(this, arguments)
    if (typeof this.onchange == 'function'){
      this.onchange()
    }
    return result
  }
}