Creating a function inside of setInterval does not refresh

Question

Creating a function inside of setInterval does not refresh

I'm facing an issue with a method that involves the use of setInterval

public retrieveMessages(route: string) {
  this.http.get(this.url + route + "?page=" + MessageService.plus)
           .subscribe(function(response) {
    if (response.json.length === 0) {
      MessageService.plus++;
      this.updateMessageList(response);
      return;
    };
  });
}

The main problem here is that any functions defined inside function must be static, otherwise they will be undefined. Although I declared 'plus' as static, I am unable to do so for 'updateMessageList'. Can anyone provide guidance on how to correct this without needing to declare my properties as static?

Appreciate your help!

javascript angular typescript setinterval

Answer 1

Answer №1

When using the function() {} syntax for callbacks inside the callback function of subscribe, your context (this) may not be captured correctly. To ensure the correct this is captured, consider using arrow functions:

this.http.get(this.url + route + "?page=" + MessageService.plus)
  .subscribe((response) => { // Use arrow function here
    if (response.json.length === 0) {
      MessageService.plus++;
      this.extractAndUpdateMessageList(response);
      return;
    };
  });

By using arrow functions, you can access instance properties inside the callback without needing to make MessageService.plus static.

Answer 2

When using the function() {} syntax for callbacks inside the callback function of subscribe, your context (this) may not be captured correctly. To ensure the correct this is captured, consider using arrow functions:

this.http.get(this.url + route + "?page=" + MessageService.plus)
  .subscribe((response) => { // Use arrow function here
    if (response.json.length === 0) {
      MessageService.plus++;
      this.extractAndUpdateMessageList(response);
      return;
    };
  });

By using arrow functions, you can access instance properties inside the callback without needing to make MessageService.plus static.

Answer 3

Answer №2

Simply make use of the following code snippet:

const self = this;

You can then refer to "self" within the callback function.

Answer 4

Simply make use of the following code snippet:

const self = this;

You can then refer to "self" within the callback function.

Creating a function inside of setInterval does not refresh

Answer №1

Answer №2

Similar questions

When attempting to use Ajax, the operation fails; however, if I directly access the URL,

Inability to update Vue.js component data even after a successful GET request

Encasing distinct HTML text with a custom color palette

How would you utilize jQuery to access the "option" array of a select control with the attribute of multiple=true by utilizing the find() method?

Effortless code formatting with VS Code for TypeScript and JavaScript

Show live updates in the input field

Unable to swap out string with text box in TypeScript

Form submission causing page to reload, getElementById function fails to return value, rendering form ineffective

Exploring methods for handling svgs incorporated in angular.js templates with webpack

Combining one-time binding, bi-directional binding in directives, and ng-repeat to create dynamic data rendering

Ionic 2: Issue with Custom Provider Resulting in "Unable to Resolve All Parameters"

Assign various JavaScript variables within a PHP foreach loop

Utilizing Typescript to ensure property keys within a class are valid

Ensure that the assistant stays beneath the cursor while moving it

Obtain the session value in React

What is the best way to switch a boolean state in React using TypeScript?

Utilize your custom types within an npm package without the need to release them to @types

Navigation on a specific page using Ionic 3

Executing intricate MongoDB collection queries using Node.js

What is the best way to integrate AJAX with a confirmation button?