Angular 7: How to subscribe to a variable change in a service?

Question

Angular

Good time of the day!
I'm learning Angular(7), tell me how to correctly subscribe to a variable change.
service MyService
- variable str
component 1
- constructor(public myService: MyService) { }
- ngOnInit() { myService.str = '222' }
component 2
- constructor(public myService: MyService) { }
- in change template {{ myService. str }} occur
How can component 2 subscribe to changes to myService.str (so that the function can be called to change str)?

Answer 1

How to make reactive data in Angular service?

Answer 2

To do this you need to use RxJs and declare the variable you want to subscribe to as a Subject
Then in the first component you can send the value using the next() method And subscribe to the changes in the second component

constructor(public myService: MyService) {
 myService.str.subscribe(value => {this.someLocalProperty = value })
}