Whats the meaning of this syntax inside subscribe?

Question

.subscribe(data=> {
    this.timezones = data;
}

.is data => the same as used in the constructor (private: data) what is the arrow and what does it do ?

export class Xx implements OnInit {

  timezones: Object;

  constructor(private api: ApiService, private data: TimezoneService) { }
  registered: boolean = false;

  ngOnInit() {
    this.data.getTimeZone().subscribe(data=> {
      this.timezones = data;
    });
  }
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions — Roberto Zvjerković, Feb 05 '19 at 13:15
Here, `data` just a local scoped variable that consumes the response after subscription. You can name it anything. And remember, it isn't related to any outer variable like in constructor or so. — Tushar Walzade, Feb 05 '19 at 13:29

Dhaval · Accepted Answer · 2019-02-05T13:59:31.830

.is data => the same as used in the constructor (private: data)
No, it's a variable which stores the response of subscription.

what is the arrow and what does it do?
Here, arrow refer for arrow function which is a new way to declare a function in ES6

This is like

.subscribe(
    function(data) {
        this.timezones = data;
    },
    function(error) {
    },
 )

With arrow function

.subscribe(
    (data) => {
        this.timezones = data;
    },
    (error) => {
    },
 )

OR

.subscribe(
    data => {
        this.timezones = data;
    },
    error => {
    },
 )

I think this article helps you to understand arrow function.

Whats the meaning of this syntax inside subscribe?

1 Answers1