distinctUntilChanged

signature: distinctUntilChanged(compare: function): Observable

Example 1: distinctUntilChanged with basic values

Example 2: distinctUntilChanged with objects

import { from } from 'rxjs/observable/from';
//Objects must be same reference
const myArrayWithDuplicateObjects = from([
  sampleObject,
  sampleObject,
  sampleObject
//only out distinct objects, based on last emitted value
const nonDistinctObjects = myArrayWithDuplicateObjects
  .pipe(distinctUntilChanged())
  //output: 'DISTINCT OBJECTS: {name: 'Test'}
  .subscribe(val => console.log('DISTINCT OBJECTS:', val));

Additional Resources

• 
  - Official docs
• Filtering operator: distinct and distinctUntilChanged
  - André Staltz