how to add delay in http request using angular?

Question

could you please tell me how to add the delay before hitting HTTP request to the server . I will give you the example .I saw a website there is button on click of + it increases the counter value and - it decrease the value.If you check the network request they are not hitting service on each button click or each increment value (if the user clicks + button many times say 5 times). They hit the service only one time when the user stops increment/decrement it's value for few second. I think they are using something like debouncing concept. can we also implement this in angular 4 .I try to implement debouncing and so that it will not fire request on each click .

here is my code https://stackblitz.com/edit/angular-zf6ysz?file=src%2Fapp%2Fapp.component.ts

 increaseCounter(){
   this.counter = this.counter +1;
   this.requestHttp(this.counter);
  }

  requestHttp(val){
    var url ="http://api.mathjs.org/v4/?expr="+val+"*"+val;
    console.log(url);
    this.http.get(url).subscribe((res)=>{
      console.log(res ,"eee")
    })

example, where I saw it, is implemented debouncing https://www.swiggy.com