Angular2 watch object/array changes (Angular2 final >= 2.1.1)

Question

I\'d like to watch an object/array, which ca be edited by a service or by a controllers routine. I thought that an Observable could watch an object/array.

My implem

Answer 1

Angular2 provides IterableDiffer (array) and KeyValueDiffer (object) to get information about differences between two checks.

NgClass is a good example https://github.com/angular/angular/blob/14ee75924b6ae770115f7f260d720efa8bfb576a/modules/%40angular/common/src/directives/ng_class.ts#L122

See also https://angular.io/docs/ts/latest/api/#!?query=differ

An example

// inject a differ implementation 
constructor(differs: KeyValueDiffers) {
  // store the initial value to compare with
  this.differ = differs.find({}).create(null);
}

@Input() data: any;

ngDoCheck() {
  var changes = this.differ.diff(this.data); // check for changes
  if (changes && this.initialized) {
    // do something if changes were found
  }
}