Angular2 restricts Http requests within a specified time interval

Question

Angular2 restricts Http requests within a specified time interval

I am a beginner with angular 2 and I have a value that is linked to user interaction that needs to be sent over http requests. The value can change multiple times per second, so I want to limit the http requests to one every 2 seconds during user interaction. I do not want to send an http request when there is no interaction. I am looking to accomplish this using a timer or interval in Angular 2:

onChange() {

  if(_interval.timerFinished) {
      http.get(.............);
      _interval.launchTimer(2000); //2 seconds
  }

}

Perhaps I can achieve this by utilizing: https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/interval.md

typescript angular intervals ionic2

Answer 1

Answer №1

I'm interested in reducing the number of http requests

To achieve this, you can connect the element by including it in the HTML as follows:

[(ngModel)] = "searchQuery" [ngFormControl]="searchQueryControl"

Then, in your code:

// Make sure to import these components:
import {FORM_DIRECTIVES, Control} from 'angular2/common';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';

constructor ( ... ) {
    //...
    this.searchQuery = '';
    this.searchQueryControl = new Control();
    //...

    this.searchQueryControl
        .valueChanges
        .debounceTime(1000)
        .distinctUntilChanged()
        .subscribe(text => {

            if(text !== '') {
              this.searchQuery = text;

              // Perform necessary actions with the text
            }
      });

    //...
}

Implementing this approach ensures that the code is executed only when there are changes in the input (

this.searchQueryControl.valueChanges

), and when no other change occurs within a second (.debounceTime(1000)). The distinctUntilChanged() method allows us to execute the code only if the value differs from the previous time it was executed. Therefore, if a user types 'asd', deletes it, and then retypes 'd' again, it will not trigger any action.

Answer 2

I'm interested in reducing the number of http requests

To achieve this, you can connect the element by including it in the HTML as follows:

[(ngModel)] = "searchQuery" [ngFormControl]="searchQueryControl"

Then, in your code:

// Make sure to import these components:
import {FORM_DIRECTIVES, Control} from 'angular2/common';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';

constructor ( ... ) {
    //...
    this.searchQuery = '';
    this.searchQueryControl = new Control();
    //...

    this.searchQueryControl
        .valueChanges
        .debounceTime(1000)
        .distinctUntilChanged()
        .subscribe(text => {

            if(text !== '') {
              this.searchQuery = text;

              // Perform necessary actions with the text
            }
      });

    //...
}

Implementing this approach ensures that the code is executed only when there are changes in the input (

this.searchQueryControl.valueChanges

), and when no other change occurs within a second (.debounceTime(1000)). The distinctUntilChanged() method allows us to execute the code only if the value differs from the previous time it was executed. Therefore, if a user types 'asd', deletes it, and then retypes 'd' again, it will not trigger any action.

Answer 3

Answer №2

Have you considered using the debounce operator? Check out more information about it here

If you're interested, you could also explore Sample or ThrottleFirst.

For additional details, take a look at this link: http://reactivex.io/documentation/operators/sample.html

Here's an example of how you can use debounce with HTTP requests:

http.get(.............).debounce(2000)

Answer 4

Have you considered using the debounce operator? Check out more information about it here

If you're interested, you could also explore Sample or ThrottleFirst.

For additional details, take a look at this link: http://reactivex.io/documentation/operators/sample.html

Here's an example of how you can use debounce with HTTP requests:

http.get(.............).debounce(2000)

Angular2 restricts Http requests within a specified time interval

Answer №1

Answer №2

Similar questions

Tips for handling numerous observables in Angular 7

Converting an array into an object by using a shared property in each element of the array as the key

Iterate through controls to confirm the accuracy of the password输入 unique

Unable to retrieve values using any = {} in TypeScript Angular 8

Ways to disperse items within another item

TypeScript is unable to detect the .sequelizerc configuration file

Navigating through a React application with several workspaces - the ultimate guide

Unleashing the Power of RXJS: Discovering the Magic of connecting Events and Tapping into Executions with retrywhen

Learn how to utilize React lazy effectively in components that utilize Redux compose without any similarities to type 'IntrinsicAttributes'

When selecting a MenuItem, only a ReactOwner has the ability to add a ref using addComponentAsRefTo(...)

Encountering issues with importing a module from a .ts file

Verify using ngIf whether an Angular component is an array or not

Tips for verifying internet connectivity and accessing stored data in localstorage

The Element type does no feature a Typescript property

Employ an asynchronous immediately-invoked function expression within the callback

Setting up Angular 7 to interact with a .Net Core Web API in Visual Studio 2017

Issue encountered while appending query parameters to HTTP request

Undefined TypeScript Interface

Avoid the occurrence of the parent's event on the child node

Having trouble resolving the '@angular/material/typings/' error?