Configuring the array interval in an Angular application

Question

Configuring the array interval in an Angular application

I'm facing an issue while attempting to use the setInterval() function to update text for the user every 3 seconds.

My attempt at looping with a for loop has not been successful - I only see 'test 03' and nothing else.

I'm struggling to find a solution.

export class MessagesComponent implements OnInit {
      items = ['test 01', 'test 02', 'test 03'];
      currentItem: any;
      private interval;

      constructor() {}

      ngOnInit() {
        for (let i = 0; i < this.items.length; i++) {
          this.interval = setInterval(() => {
            this.currentItem = this.items[i];
          }, 3000);
        }
      }
    }

{{ currentItem }}

Any assistance would be greatly appreciated!

javascript angular typescript setinterval

Answer 1

Answer №1

Consider implementing it in a slightly different manner.

The variable pointer is utilized to track the current content for display. It increments by 1 at each interval until reaching a value greater than 2, after which it resets to 0.

export class MessagesComponent implements OnInit {
  items = ['example 01', 'example 02', 'example 03'];
  currentItem: any;
  private pointer: number = 0;

  constructor() {}

  ngOnInit() {
      this.interval = setInterval(() => {
        this.currentItem = this.items[this.pointer];
        this.pointer++;
        if (this.pointer > 2) { this.pointer = 0 };
      }, 3000);
  }
}

Answer 2

Consider implementing it in a slightly different manner.

The variable pointer is utilized to track the current content for display. It increments by 1 at each interval until reaching a value greater than 2, after which it resets to 0.

export class MessagesComponent implements OnInit {
  items = ['example 01', 'example 02', 'example 03'];
  currentItem: any;
  private pointer: number = 0;

  constructor() {}

  ngOnInit() {
      this.interval = setInterval(() => {
        this.currentItem = this.items[this.pointer];
        this.pointer++;
        if (this.pointer > 2) { this.pointer = 0 };
      }, 3000);
  }
}

Answer 3

Answer №2

Give this a shot:

export class MessagesComponent implements OnInit {
  words = ['example 01', 'example 02', 'example 03'];
  currentWord: any;
  private timer;

  constructor() {}

  ngOnInit() {
    for (let i = 0; i < this.words.length; i++) {
      this.timer = setInterval(() => {
        this.currentWord = this.words[i];
      }, 3000 * i);
    }
  }
}

{{ currentWord }}

Answer 4

Give this a shot:

export class MessagesComponent implements OnInit {
  words = ['example 01', 'example 02', 'example 03'];
  currentWord: any;
  private timer;

  constructor() {}

  ngOnInit() {
    for (let i = 0; i < this.words.length; i++) {
      this.timer = setInterval(() => {
        this.currentWord = this.words[i];
      }, 3000 * i);
    }
  }
}

{{ currentWord }}

Answer 5

Answer №3

If you're enjoying the functionality of rxjs,

import { timer } from 'rxjs';
import { tap } from 'rxjs/operators';

ngOnInit() {
  timer(0, 3000)
    .pipe(
      tap(v => {
        this.currentItem = this.items[v%3]
      })
    )
    .subscribe(console.log);
}

With less code and no need for loops or intricate logic involved :)

You can take it a step further with

export class MessagesComponent implements OnInit {
  private timer$ = timer(0, 3000);
  ngOnInit() {
    // The for loop can be completely eliminated
  } 
}

In your html, simply use

{{ items[(timer$ | async) % 3] }}

By utilizing the async pipe and rxjs, you can achieve the same goal with just one line of code and ditch the messy for-loop.

Check out a demo here

Answer 6

If you're enjoying the functionality of rxjs,

import { timer } from 'rxjs';
import { tap } from 'rxjs/operators';

ngOnInit() {
  timer(0, 3000)
    .pipe(
      tap(v => {
        this.currentItem = this.items[v%3]
      })
    )
    .subscribe(console.log);
}

With less code and no need for loops or intricate logic involved :)

You can take it a step further with

export class MessagesComponent implements OnInit {
  private timer$ = timer(0, 3000);
  ngOnInit() {
    // The for loop can be completely eliminated
  } 
}

In your html, simply use

{{ items[(timer$ | async) % 3] }}

By utilizing the async pipe and rxjs, you can achieve the same goal with just one line of code and ditch the messy for-loop.

Check out a demo here

Configuring the array interval in an Angular application

Answer №1

Answer №2

Answer №3

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