knockout-change-subscriber

A small subscribable extension to keep track of changes to an observable

Why not subscribe(observable, null, 'arrayChange')?

The native array change subscribe function does not work well with computed arrays nor normal observables.

I.e. neither of these will work

var observable = ko.observable();
var observableArray = ko.observableArray();
var computedObservableArray() = ko.computed(function(){
  return observableArray();
}, this, "arrayChange");

observable.subscribe(function(changes){
  // never executes
}, null, "arrayChange");

observableArray.subscribe(function(changes){
  // works
}, null, "arrayChange");

computedObservableArray.subscribe(function(changes){
  // never fires
}, null, "arrayChange");

Dependencies

jQuery >= 1.1.4 (used for $.extend)
underscore.js ~1.8.2 (used for _.filter)
bower-knockout-mapping ~2.5.0 (or just knockout-mapping)
knockout.js >= 3.0.0

Installation

Can be installed via bower package

bower install --save knockout-change-subscriber

... or by cloning the repository

git clone git@github.com:esbenp/knockout-change-subscriber.git

... or by grabbing a zip of the latest release

Small example

See examples directory for more

var observable = ko.observable("Observable 1");
var observableArray = ko.observableArray([
  {id: ko.observable(2), name: ko.observable("Test")}
  ]);
var computedObservable = ko.computed(function(){
  return observable();
}, this);
var computedObservableArray = ko.computed(function(){
  return observableArray();
}, this);

observable.changeSubscriber(function(newValue, oldValue){
  console.log("observable", newValue, oldValue);
});

observableArray.changeSubscriber(function(additions, deletions){
  console.log("observableArray", additions, deletions);
});

computedObservable.changeSubscriber(function(newValue, oldValue){
  console.log("computedObservable change", newValue, oldValue);
});

computedObservableArray.changeSubscriber(function(additions, deletions){
  console.log("computedObservableArray change", additions, deletions);
});

observable("Yo");
observableArray.push({id: ko.observable(3), name: ko.observable("Yo")});
observableArray.remove(function(entry){
  return entry.id() === 2;
});

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.