ngx-link-preview

The Open Graph link preview component for Angular 6+

⇨ DEMO

Installation

npm install --save ngx-link-preview

yarn add ngx-link-preview

Features

• Configurable preview
• Render array of links
• Parse links in string
• Loading indicator
• Theming: default and modern theme included

Requirements

• Angular 6+
• You will need to create an endpoint at your backend to parse an url for meta tags.
  See info below

Component configuration

1. Import to your module

@NgModule({
   imports: [
      NgxLinkPreviewModule,
      ...
   ]
})
export class AppModule { }

2. Use as regular component

<ngx-link-preview></ngx-link-preview>

3. Parameters: Configure the preview

• Two required parameters:

1. [apiRoute]="myApiRoute"

apiRoute accepts any url, where you want to retrieve the metadata from. The target url will be attached by the component as base64 urlencoded query parameter.

/** API route where to get the meta data from, component will build the full request url
 * Schema: api.example.com/api/get-meta-data?url=d3d3LmV4YW1wbGUuY29t
 */
@Input()
public apiRoute: string;

2. [getApiEndpoint$]="apiCallbackFn"

A generic callback function that returns an observable, that runs the api request on subscription. You can use the default Angular HttpClient method, or your configured backend wrapper observable.

/** Method that does the API request, provide as class member arrow function from parent */
@Input()
public getApiEndpoint$: (requestUrl: string) => Observable<any>;

For example:

public apiCallbackFn = (route: string) => {
   return this.http.get(route);
};

• Optional parameters

• Links that should be rendered, default: []

/** Plain links string array */
@Input()
public links: string[] = [];

• Input string that should be parsed for links, can be combined with links[]

/** Input string to parse for links */
@Input()
public parseForLinksStr: string;

• Query parameter name, default: 'url'

/** Target url will be attached as encodeURI(btoa(url)), so it must be decoded on the server */
@Input()
public queryParamName = 'url';

• Show image in preview, default: true

/** boolean: show image in preview */
@Input()
public showImage = true;

• Show site name in preview, default: true

/** boolean: show site name in preview */
@Input()
public showSiteName = true;

• Show title in preview, default: true

/** boolean: show title in preview */
@Input()
public showTitle = true;

• Show description in preview, default: true

/** boolean: show description in preview */
@Input()
public showDescription = true;

• Show url in preview, default: false

/** boolean: show link url in preview */
@Input()
public showLinkUrl = false;

• Use cache, default: true

/** boolean: use cache to display previews faster on next rendering */
@Input()
public useCache = true;

• Max cache age in milliseconds, default: 7 days

/** number: max age the data cache of a link preview should be used */
@Input()
public maxCacheAgeMs = 1000 * 60 * 60 * 24 * 7; // 7 days

• Show loading indicator, default: true

/** boolean: show loading indicator */
@Input()
public showLoadingIndicator = true;

• HTML link <a href="..."></a> should be clickable, default: false

/**
* boolean: whether the <a href="..."></a> link should be clickable.
* This is a question of context security. Otherwise use (previewClick) event.
*/
@Input()
public useHtmlLinkDefaultClickEvent = false;

• HTML link target, default: '_blank' (new tab)

/**
* HtmlLinkTarget: where the HTML link should be opened on click.
* Only has an effect if [useHtmlLinkDefaultClickEvent]="true"
*/
@Input()
public htmlLinkTarget: HtmlLinkTarget = '_blank';

• Event emits the URL on click

/** Event emitter: on click to handle the click event, emits the clicked URL */
@Output()
public previewClicked = new EventEmitter<string>();

<!-- $event: string is URL --> 
(previewClick)="previewClicked($event)"

Theming

The package ships a default and a modern theme. The modern theme crops the preview image, what might conclude in unintended results. To use the modern theme, just pass the css class:

<ngx-link-preview class="modern"></ngx-link-preview>

Feel free to create more themes and submit a pull request or open an issue!

You can use this skeleton: (click to show)

.ngx-link-preview-container {
   .og-link-preview {
      &:hover {
      }
      .row {
         .col {
            &.preview-image {
            }
            &.text-data {
            }
            .image {
               img {
               }
            }
            .title {
            }
            .description {
            }
            .header {
               .site-name {
               }
            }
            .footer {
               .url {
               }
            }
         }
      }
   }
}

Loading spinner

You can customize the loading spinner by passing your spinner as content of the component:

<ngx-link-preview>
    <my-spinner-component></my-spinner-component>
</ngx-link-preview>

<!-- or alternatively (any child element): -->
<ngx-link-preview>
    <div class="spinner"></div>
</ngx-link-preview>

Endpoint configuration

Node.js example

With node.js you can use url-metadata

import urlMetadata from 'url-metadata';

public getMetadata(request: Request, response: Response) {
   let { url } = request.query;
   url = this.decodeSafeUrl(url);
   
   urlMetadata(url).then(
      resp => {
         response.send(resp);
      },
      error => {
         response.send(error).status(500);
      }
   );
}

public decodeSafeUrl(value: string): string {
   const valueBase64 = decodeURI(value);
   return Buffer.from(valueBase64, 'base64').toString('utf8');
}

PHP example

$router->get('/meta-tags', function() {
  $url = $_GET['url'];
  $urlDecoded = base64_decode(urldecode($url));
  ini_set('user_agent', 'Mozilla/4.0 (compatible; MSIE 6.0)');
  $sites_html = file_get_contents($urlDecoded);

  $html = new DOMDocument();
  @$html->loadHTML($sites_html);

  $metaTags = [
      'title' => '',
      'description' => '',
      'image' => '',
      'canonical' => '',
      'url' => '',
      'author' => '',
      'availability' => '',
      'keywords' => '',
      'og:description' => '',
      'og:determiner' => '',
      'og:image' => '',
      'og:image:height' => '',
      'og:image:secure_url' => '',
      'og:image:type' => '',
      'og:image:width' => '',
      'og:locale' => '',
      'og:locale:alternate' => '',
      'og:site_name' => '',
      'og:title' => '',
      'og:type' => '',
      'og:url' => '',
      'price' => '',
      'priceCurrency' => '',
      'source' => '',
  ];

  foreach ($html->getElementsByTagName('meta') as $meta) {
      $property = $meta->getAttribute('property');
      $content = $meta->getAttribute('content');
      if (strpos($property, 'og') === 0) {
          $metaTags[$property] = $content;

          if ($property === 'og:title') $metaTags['title'] = $property;
          if ($property === 'og:description') $metaTags['description'] = $property;
          if ($property === 'og:image') $metaTags['image'] = $property;
      }
  }
  $metaTags['canonical'] = $urlDecoded;
  $metaTags['url'] = $urlDecoded;

  return response()->json($metaTags);
});