Angular 2 - Validate image URLs with JavaScript code

Introduction

When working with images in Angular 2, it's important to ensure that the URLs provided are valid and can be loaded without errors. In this article, we'll show you how to validate image URLs using JavaScript code in Angular 2.

Validating Image URLs

First, we'll create a function that takes a URL string as a parameter and returns a boolean value indicating whether the URL is valid or not. Here's the code:

<pre><code>function isValidImageUrl(url) {
  var img = new Image();
  img.src = url;
  return img.complete && img.naturalWidth !== 0;
}</code></pre>

In this function, we create a new Image object and set its src property to the URL we want to validate. We then check if the image has loaded successfully by checking the values of its complete and naturalWidth properties. If both properties are true, then the URL is considered valid.

Now, we can use this function in our Angular 2 code to validate image URLs before using them. Here's an example:

<pre><code>import { Component } from '@angular/core';

@Component({
  selector: 'app-image',
  templateUrl: './image.component.html',
  styleUrls: ['./image.component.css']
})
export class ImageComponent {
  imageUrl: string = 'https://example.com/image.jpg';
  isValidUrl: boolean;

  validateUrl() {
    this.isValidUrl = isValidImageUrl(this.imageUrl);
  }
}</code></pre>

In this example, we import the necessary modules and create a new component that contains an image URL and a boolean value indicating whether the URL is valid or not. We also create a function called validateUrl() that calls our isValidImageUrl() function and updates the isValidUrl property accordingly.

Finally, we can use the isValidUrl property in our HTML code to display a message or take other actions based on the validity of the image URL. Here's an example:

<pre><code><div *ngIf="isValidUrl">
  <img [src]="imageUrl" alt="Image">
</div>
<div *ngIf="!isValidUrl">
  Invalid image URL.
</div></code></pre>

In this example, we use the *ngIf directive to display different content based on whether the image URL is valid or not. If the URL is valid, we display the image using the [src] attribute. If the URL is invalid, we display an error message instead.

Conclusion

Validating image URLs is an important step in working with images in Angular 2. By using JavaScript code, we can ensure that the URLs provided are valid and can be loaded without errors. We hope this article has been helpful in showing you how to validate image URLs in Angular 2.