Extract id from URL using Angular (2+ till latest)

Subscribing and Unsubscribing to Route Parameters

1. Make sure you have configured a route that expects a parameter like so:

{path: 'item/:id', component: SomeItemComponent}

2. Declare a variable for your route subscription. Import ActivatedRoute (not ActiveRoute) and inject it in your component constructor.

private routeSub: Subscription;
constructor(private route: ActivatedRoute) { }

3. Inside ngOnInit in the same component, you can access the data in the params observable by subscribing to it like so:

ngOnInit() {
  this.routeSub = this.route.params.subscribe(params => {
    console.log(params) //log the entire params object
    console.log(params['id']) //log the value of id
  });
}

4. Inside ngOnDestroy, unsubscribe to prevent memory leaks.

ngOnDestroy() {
  this.routeSub.unsubscribe();
}

Update – January 2021

There is a big difference between route.params and route.queryParams.

route.params, when subscribed to, returns an object with keys (that come from your route parameters, see step 1) and string values that are provided when navigating to the route. For example:

example.com/item/1

{
  itemId: '1'
}

route.queryParams, when subscribed to, returns an object with keys and string values that come from the query string (wiki) in the URL. For example:

example.com/welcome?var1=abc&var2=cde

{
  var1: 'abc',
  var2: 'cde'
}

route.queryParams will be undefined if a query string is not present in the URL. I believe OP, and some users in the comments have mistakenly used this instead of route.params.