private data : Observable<Array<any>>;
  private dataObserver: Observer<Array<any>>;
  private sub : Subscription;
  private items: <Array<any>>;

  ngOnInit() {
     this.items = itemService.getItems();
     this.data = new Observable<Array<any>>(observer =>{
        this.dataObserver = observer;
     });
     this.data.subscribe(
        x => console.log('onNext: %s', x),
        e => console.log('onError: %s', e),
        () => console.log('onCompleted')
     );
     this.dataObserver.next(this.items);
  }


private start(){

  //change values of the array in an interval
  let loop = Observable.interval(250)
  let i=0;
  self.sub = loop.subscribe(() => {
      if(self.items[0]){
        self.items[0].id= i;
        if(i<100) i++;
        else i=1;
      }
  })
}

// 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
  }
}

import { Component, DoCheck } from "@angular/core";
export class LangListUserComponent implements DoCheck {

  constructor(private _languageService: LanguageService)
  {}

  ngDoCheck() {
    /** Get available lang */
    this.oLanguages = this._languageService.getLanguageList();
    this.setCurrentLang(this.oLanguages);
  };
}

import { DoCheck, KeyValueDiffers, KeyValueChangeRecord } from '@angular/core';

private _differ: any;

    constructor(private _differs: KeyValueDiffers) {
            this._differ = _differs.find({}).create();
        }

ngDoCheck() {
        const change = this._differ.diff(this.student);
        if (change) {
            change.forEachChangedItem(
                (record: KeyValueChangeRecord<any, any>) => {
                    console.log(record.key + ': ' +  record.previousValue + '=>' + record.currentValue) });

            change.forEachRemovedItem(
                    (record: KeyValueChangeRecord<any, any>) => {
                        console.log(record.key + ': ' +  record.previousValue + '=>' + record.currentValue) });

            change.forEachAddedItem((record: KeyValueChangeRecord<any, any>) => {
                        console.log(record.key + ': ' +  record.previousValue + '=>' + record.currentValue) });
        }
    }