timer in angular 8 with code examples 2

Angular is a popular framework for building web applications, and it provides a powerful set of tools for managing state and logic. One of the most common tasks in web development is working with timers, and Angular provides a number of ways to create and manage timers in your application. In this article, we will explore how to create and use timers in Angular 8, with code examples.

First, let's start by creating a new Angular 8 project. You can do this by running the following command in your terminal:

ng new my-timer-app

This will create a new directory called my-timer-app that contains the basic structure of an Angular 8 application.

Once your project is set up, you can create a new component called timer by running the following command:

ng generate component timer

This will create a new directory called timer in the src/app folder, containing the component's template, style, and logic.

Now, let's take a look at some examples of how to use timers in Angular 8.

Example 1: Using setTimeout()

The setTimeout() function is a JavaScript function that allows you to execute a function after a specified amount of time. In Angular 8, you can use this function to create a timer that updates a component's state after a certain amount of time.

import { Component } from '@angular/core';

@Component({
  selector: 'app-timer',
  template: `
    <div>
      <p>{{ count }}</p>
      <button (click)="startTimer()">Start Timer</button>
    </div>
  `,
  styles: []
})
export class TimerComponent {

  count = 0;

  startTimer() {
    setTimeout(() => {
      this.count++;
    }, 1000);
  }

}

In the above example, the startTimer() function uses setTimeout() to increment the count variable by 1 every second. The template of the component displays the current value of count and a button that starts the timer when clicked.

Example 2: Using setInterval()

The setInterval() function is similar to setTimeout(), but it executes a function repeatedly at a specified interval. In Angular 8, you can use this function to create a timer that updates a component's state repeatedly.

import { Component } from '@angular/core';

@Component({
  selector: 'app-timer',
  template: `
    <div>
      <p>{{ count }}</p>
      <button (click)="startTimer()">Start Timer</button>
      <button (click)="stopTimer()">Stop Timer</button>
    </div>
  `,
  styles: []
})
export class TimerComponent {

  count = 0;
  intervalId: any;

  startTimer() {
    this.intervalId = setInterval(() => {
      this.count++;
    }, 1000);
  }

  stopTimer() {
    clearInterval(this.intervalId);
  }

}

In the above example, the startTimer() function uses setInterval() to increment the count variable by 1 every second. The template of the component displays
the current value of count and two buttons, one that starts the timer when clicked, and another one that stops the timer. The stopTimer() function uses the clearInterval() function to stop the timer.

Example 3: Using the async pipe

The async pipe is a built-in pipe in Angular that allows you to easily subscribe to an observable and automatically unsubscribe when the component is destroyed. This can be useful when working with timers, as it allows you to easily update the view when the timer's state changes.

import { Component, OnInit, OnDestroy } from '@angular/core';
import { interval } from 'rxjs';

@Component({
  selector: 'app-timer',
  template: `
    <div>
      <p>{{ timer$ | async }}</p>
      <button (click)="startTimer()">Start Timer</button>
      <button (click)="stopTimer()">Stop Timer</button>
    </div>
  `,
  styles: []
})
export class TimerComponent implements OnInit, OnDestroy {

  timer$;
  subscription;

  ngOnInit() {
    this.timer$ = interval(1000);
  }

  startTimer() {
    this.subscription = this.timer$.subscribe(val => {
      console.log(val);
    });
  }

  stopTimer() {
    this.subscription.unsubscribe();
  }

  ngOnDestroy() {
    this.stopTimer();
  }

}

In the above example, we are using the interval method from the rxjs library to create an observable that emits a value every second. The template uses the async pipe to subscribe to the observable and display the current value. The startTimer() and stopTimer() methods control the subscription to the observable.

In summary, Angular 8 provides a variety of ways to work with timers in your application. Whether you use setTimeout(), setInterval(), or the async pipe, you can easily create and manage timers that update your component's state and view. It's important to keep in mind that when working with timers, it's important to stop them when the component is destroyed to avoid memory leaks.

Popular questions

1. How do you create a new Angular 8 project?
   Answer: You can create a new Angular 8 project by running the command ng new my-timer-app in your terminal.

2. How do you create a new component in Angular 8?
   Answer: You can create a new component in Angular 8 by running the command ng generate component timer.

3. How can you use the setTimeout() function in Angular 8?
   Answer: The setTimeout() function can be used in Angular 8 to execute a function after a specified amount of time. You can use this function to create a timer that updates a component's state after a certain amount of time.

4. How can you use the setInterval() function in Angular 8?
   Answer: The setInterval() function can be used in Angular 8 to execute a function repeatedly at a specified interval. You can use this function to create a timer that updates a component's state repeatedly.

5. How can you use the async pipe in Angular 8 for timers?
   Answer: The async pipe can be used in Angular 8 to subscribe to an observable and automatically unsubscribe when the component is destroyed. This can be useful when working with timers, as it allows you to easily update the view when the timer's state changes. The interval method from the rxjs library can be used to create an observable that emits a value every second.

Tag

Timers